530 MOLLUSCA. 
3. Anodonta exilior. (Tab. XL. figg. 8-11.) 
Anodon glabrus (sic!), Sowerby, in Reeve’s Conch. Icon. xvii., Anodon, t. 25. fig. 97 (1870)' [nec 
Anodonta glabra, Villa (1841), Bourg. (1888) ; nec F. J. Schmidt (1847)]. 
Anodonta exilior, Lea, Proc. Acad. Phil. 1871, p. 188°; Journ. Acad. Phil. (2) viii. p. 24, t. 7. 
fig. 21°,=Obs. Gen. Unio, xiii. p. 28, t. 7. fig. 21°; Fisch. & Crosse, Miss. Scient. Mex., 
Moll. ii. p. 520°. 
Anodonta viridana, Clessin, in Martini & Chemnitz, Syst. Conch.-Cab. ed. 2, Anodonta, p. 226, 
t. 75. fig. 5 (copied from Sowerby) (1875-76) °. 
In general appearance not unlike the European 4A. piscinalis, Nilsson; somewhat winged and rostrated, 
moderately swollen; fore part short, abruptly rounded, in some specimens descending nearly in a perpen- 
dicular direction and thus forming an obtuse angle with the dorsal margin before the summits; hinder 
part distinctly rostrated, its upper margin descending almost in a straight oblique line behind the little 
prominent wing, its ventral margin ascending in a less degree, in some specimens scarcely at all. 
Summits not prominent, with a few (4) undulating concentric plaits, worn off, showing a chalk-white layer 
of shelly matter, and beneath it one of brownish-bronze-colour. Outer surface glossy, dark brownish- 
green, with rather numerous, more or less distinct, dark-coloured interruptions of growth. Inside bluish 
or violet-bluish, somewhat iridescent, towards the summits more or less orange or pink. 
a. Long. 69; alt. vert. 43, ale 424, diam. 23 millim. Vertices in 2 long. 
b. ” 60 > 99 35, 99 36, 39 20 x9 39 2 99 
Cc. » 08 5 ” 313, ” 353; 3 22 ” ” Z 9 
d. 9 7 > ” 314, ” 313, 99 2 9 ” ¢ ” 
é. ” 48 3 ” 24, 9 303, ” 144 ” ” 2 ” 
f. » O0; ” 23, ,, 32, » 16 29 ” z 2 
All these measurements taken from specimens from Vera Cruz, as also our figures 8-11. 
Hab. K. Mexico: Vera Cruz (Ff. D. Godman); Mexico, without nearer indication of 
locality (Suwerby1; Wheatley; Uhde, in Mus. Berol.). 
4. Anodonta montezuma. 
Anodonta montezuma, Lea, Trans. Am. Phil. Soc. (2) vill. p. 240, t. 23. fig. 55 (1841) +, =Obs. Gen. 
Unio, iii. p. 78, t. 19. fig. 55°; Sowerby, in Reeve’s Conch. Icon. xvi., Anodon, t. 36. fig. 143°; 
Clessin, in Martini & Chemnitz, Syst. Conch.-Cab. ed. 2, Anodonta, p. 220, t. 72. figg. 7, 8*. 
A small, somewhat wrinkled shell, without any striking peculiarities. 
Long. 38; alt. vert. 25, ale 24, diam. 15 millim. Vertices in # long. 
Hab. Cuntrat America (Dr. Jay 1). 
5. Anodonta chalcoensis. 
? Anodonta impura, Say, in New Harmony Disseminator of Useful Knowledge, no. 23, p. 355 
(1829)'; Complete Writings, ed. Binney, p. 189*; Fisch. & Crosse, Miss. Scient. Mex., 
Moll. ii. p. 537°. 
Anodonta chalcoensis, Crosse & Fisch. Journ. de Conch. xli. p. 110 (1893) *; Miss. Scient. Mex., 
Moll. ii. p. 522, t. 64. fige. 7, 7a°. 
Oval, rounded before and behind, ventral margin well arcuated ; periostracum olivaceous or blackish-brown, 
somewhat lamelluted in the hinder part. 
Hab. Cuntran Mexico: Lake of Chalco (Biart, Sallé+®) ; t between Mexico city and 
Tacubaya (Say 1°). 
The identity cf Say’s species with A. chalcoensis is rendered probable by the words 
