"There is a difference of authorities as to dates of publication.
	The work was issued in 14 livraisons. Englemann gives 1832-33 as
	dates of issue; Coues cites only 1832; the Library of the British
	Museum (Natural History), quoting from the 'Bibliographie de la 
	France' assigns Livrs. 1-7 to 1832 and the rest of the book to 1833;
	the title-page of the 'Index' of the work in question bears the date
	1832 (probably in the 11th or 12th livr.), while the author's preface
	is dated December 1831. .... Sherborn says ... 'Pp.1-112, 1832;
	113-172, & pls. I-XLIII, 1833' ".
	

	"Index Général et Synoptique des Oiseaux du Genre Trochilus"

Coues (1879) dates the entirety of this work to 1832.

Coues' discussion (p.664) of Lesson's works on hummers is of interest, a portion reads:

	  These three books may be found bound in different ways: generally, with text of all three
	together, and plates in three separate vols. Index Général belongs to "Trochilidées", as per
	title of the latter, but is separately titled and paged. There are in the whole series 86+66+
	66=218 plates, but only about 110 species are treated. There are both plain and colored
	issues of the plates -- both together in the copy examined.
	  These three books are hard to get the hang of; the titles are so curiously mixed up that
	there is endless confusion in citing them, especially at second-hand. The three separate
	series are perfectly distinct works, bibliographically speaking, yet represent a single mono-
	graph of the Hummers, with titles enough alike to be confusing, yet not different enough to
	be distinctive until they are studied out. The following summary may therefore be useful:
		LESS., "Ois.-Mouch., pp. i-xlvj, 1-233, pll. 1-48 bis., 49-85 (86 plates). Date, 1829
		LESS., "Colibris et Suppl. Ois.-Mouch., pp. i-x, 1-196 (Colibris, p.1-90; Suppl. O.-M.,
		  pp. 91-192). Colibris, pll.1-12, 12bis., 13bis. 14-25. Suppl. O.-M.., pll.1-39 (66 plates in
		  the two series). Date, 1830-'31.
		LESS., "Trochilidées,". pp. i-iv, 1-171, pll. 1-66.  Date, 1832.
		Index Général, pp.i-xliij, no plates. Date, 1832.
	  Lesson's work on the Hummers is notable as one of the earliest extensive monographies
	of this extraordinary family of birds, being only preceeded byt that of Audebert and Vieillot.
	It treats, however, of only about one-third of the species now known, and its claims as a con-
	tribution to science are not of the highest. The plates are finely finished, being good work
	of this French kind, and when colored become very pretty pictures; but the technic of the 
	work, as already hinted, is of moderate merit. Many new species and several new genera are
	named, and various species are renamed even when the author knew and cited their prior
	designations -- a reprehensible habit which Lesson not seldom indulged.
	  It appears from Rev.Zool., iii, 1840, p.71, that Lesson intended to publish a fourth vol., but
	it remained ined.

I analyzed the copy online and here's are the component parts I found:

[1leaf],      i-iv,      i-xlviii,      pg. 1-168,    169-171   
title page,   preface,   Index Gen.,    text,      table (page index)

The bibliographer's "formula" for the collation of the copy online at Gallica, 
ie. the signature formula, is below.  
The numbers in rounded parenthesis indicate the number of leaves per signature. 

[1 leaf], a(2), a-e(4)f(2), 1-10(8)11(4), [unsigned leaves(2)] 

This formula may be interpreted as such:  

The leaf in the beginning is the title page.  
	The title page could have been printed from anywhere between 1831 and 1833.  
	In my opinion it most likely was printed in 1832 or 1833, since it mentions 
	the "Index General", and was most likely issued in 1833 as a cover page for 
	all livrasons once assembled together.  
	(Incidentally, I have requested on ILL a copy of the prepublication prospectus.  
	I will let you know if that turns anything up.) 

The first signature with the lowercase "a" includes the preface pages i-iv 
(one signature of 2 leaves).  
	Since the preface is dated 1831 with a reference in the last paragraph to 1833, 
	it was most likely printed in 1832 as Coues and many others assume, 
	but was printed separately from the "Index General".   

The second grouping of lower case signatures, sig. a-f, is the "Index General".  
Sigs. a-e consist of 4 leaves each (i.e. 8 pages; 8 pgs. X 5 sigs. = 40 pgs.).  
Sig. f consists of 2 leaves (i.e. 4 pgs.).  
	Since signature "a" often starts a significant text page, 
	the "a" marking at the bottom of the page is often omitted, as was done here.  
	Since sig. b is proceed by 8 leaves, or, 16 pages, it is implied that the title 
	page of the "Index General" is the first leaf of sig. a.  
	Because the Index General does not refer to any pages within the text, 
	you may rest assured that the information in it was indeed published in 1832 
	as the title page states.  

The numbered signatures as you know are the text proper.  
Sigs. 1-10 (each in 8 leaves/16 pages), and sig. 11 (4 leaves/8 pages).  
	Zimmer (contrary to Coues) indicates that Livraisons 8-14 (pg. 113-172) 
	were likely issued in 1833.  Based on bibliographic evidence alone, 1833 seems possible 
	since there is a definite difference between the sigs. 1-7, and 8-11 
	(as you noticed, sig. 1-7 have a period following the number, while sig. 8-11 do not).  
	However, such an assumption without further investation, i.e. checking paper quality, 
	or checking the paper for watermarks, is not possible since we do not have an actual copy 
	before us. 
	I personally think Zimmer is correct, since there are so many other sources that cite 1833 
	as the end publication date. 

The Table following the text is numbered in sequence with the text, pg. 169-171, but is unsigned.  
Since it is the table of contents (or index, as it has come to be called) that includes page 
numbers referred to within the text, we can assume it was not printed at the same time as the text.  
It was printed afterwards, as indexes often are. If we continue on with Zimmer's assumption on an 
1833 end publication date, then I would surmise the table of contents was printed and issued in 1833.

 I.  In each of these three works there is a small bound insert written and signed by Sherborn.

 ...
 ...

  
 III. I spent most time working on "Les Trochilidées" because it seemed to me 
 that our problems are all in this. CDS has dates and page numbers for every one of 
 the 13 livraisons with no groupings. They are:

	

			

				
livraison
				
pages. Date
				
Month.
				
Year
			
	
		

			

				
1
				
1-16
				
May
				
1832
			
			

				
2
				
 -32
				
July
				
1832
			
			

				
3
				
 -48
				
July
				
1832
			
			

				
4
				
 -64
				
Oct.
				
1832
			
			

				
5
				
 -80
				
Nov.
				
1832
			
			

				
6
				
 -96
				
Dec.
				
1832
			
			

				
7
				
 -112
				
Dec.
				
1832
			
			

				
8
				
 -128
				
Feb.
				
1833
			
			

				
9
				
 -144
				
Apr.
				
1833
			
			

				
10
				
 -172
				
Aug.
				
1833
			
			

				
11
				
i-xvi
				
Aug.
				
1833
			
			

				
12
				
xvii-xxxii
				
Sep.
				
1833
			
			

				
13
				
xxxiii-xliii
				
Dec.
				
1833
			
			
		

        Comments: you will have realised/remembered that pp.i-xliii 
        comprise the Index Général et Synoptique and 
        that this has a title page dated 1832 (on which someone has lightly pencilled 1833).
 
	I was pretty certain that CDS would have found these dates in the Bibliographie de France 
	and so I retraced his steps (just as I did for Lesson's Traité d'Orn. following the trails laid, 
	I thought, by Mathews, but I now bet that somewhere we shall find that CDS did that for Mathews)
 
   	and here is what I found:
 


			

				
 Bibliographie de France details per livraison
			
	
	

			

				
livraison
				
Entry No. 
				
Page
				
Issue/Year
				
Publ. date of BDF issue
				
Plates rept'd
			
	
		

			

				
1
				
2431
				
284
				
20/1832
				
 19 May 1832
				
5
			
			

				
2
				
3523
				
412
				
29/1832
				
21 July 1832
				
5
			
			

				
3
				
4484
				
523
				
37/1832
				
15 Sep. 1832
				
5
			
			

				
4
				
5143
				
604
				
42/1832
				
20 Oct. 1832
				
5
			
		
	
        4.           5143           604          42/1832              20 Oct. 1832                     5
        5.           5515           649          45/1832              10 Nov. 1832                     5
        6.           6086           712          49/1832               8 Dec. 1832                     5
        7.           6334           743          51/1832              22 Dec. 1832                     5
        8.           1061           126           8/1833                23 Feb. 1833                   
        9.           2022           236          15/1833              13 April 1833 
        10.          4172           484          31/1833              3 August 1833
        11.          4447           516          33/1833              17 August 1833
        12.          5262           610          39/1833              28 Sept. 1833
        13.          6874           805          51/1833              21 December 1833
 
        Comments: a) I find I did not note down the number of plates per issue in 1833, but I think it will have been 5 each right to the end -- except there is one extra in there somewhere as the total was advertised as 66 plates (with which Zimmer agreed); b) Zimmer was economical with the truth about the information in the British Museum, and so probably did not see Sherborn's detailed notes with pagination given (perhaps he drew on the published BM library catalogue of about 1903 -- which I did not check); c) There is nothing within the entries in the Bibl. de France to show the pagination of any of the livraisons. CDS must either have got that information from elsewhere or he guessed. Based on how he displayed the data compared to that which he displayed for the "Histoire Naturelle des Oiseaux Mouches" I believe that he did not guess! CDS, like CWR, was too precise a bibliographer to do that. It follows that 1832 on the title page to the Index is misleading.
 
        Again the plates only have French vernacular names.