CUASS TALE. fA. 
PLATE I. 
Genus CASTALIA. Lamarck. 
Testa fluviatilis, bivalvis, bimusculosus, trapezoidea, vel 
subtrigona, extisepidermide olivaceo-fusco, sewviridi 
indutd, intusmargaritaced ; dentibus rectangulariter 
serratis ; umbonibus tumidis, plerumque divari- 
catim sulcatis. 
Shell fluviatile, bivalve, bimuscular, trapezoid, or sub- 
trigonal, covered without with an olive brown or 
green epidermis; pearly within; teeth rectangularly 
generally divergently 
serrated; umboes tumid; 
sulcated. 
The Castalie differ in few definable characters from 
Unios ; although there is a general appearance in 
them which makes it not difficult to distinguish them. 
The most striking character is the serration of the teeth 
by grooves directly across them. It is this which in- 
clined Lamarck to separate this genus from the rest of 
the Nayades, and place it next to Trigonia, with which 
it has hardly any other relation. The Castalie are all, 
with one partial and one doubtful exception, natives of 
They differ from the Hyriz in the 
ions on the dorsal margin. 
South America. 
absence of wing-like exp 
Only one species was mentioned originally by Lamarck. 
Hupé enumerates seven. We add one from South 
Carolina, one shell of doubtful character and locality, 
and several others which have been confounded with 
those already known, bringing the number to thirteen. 

Species 1. (Mus. Sowerby.) 
CasTALIA AMBIGUA.—Cas. testd@ crassd, tumidissimd, 
trapezoided, obliquod, versus marginem ventralem 
levigatd, versus umbones rugis crassis obtusis 
medio convergentibus impressa ; 
obliquo elevatim angulato, ared postangulari com- 
tatere pestico 
planata, medio subsuleatd, margine dorsali de- 
presso, declivi ; latere antico brevissimo ; wmboni- 
bus prominentibus, tumidis, angulatis. 
Tue ampicuous Castatia, Shell thick, very tumid, 
trapezoidal, oblique, smooth towards the ventral 
margin, impressed towards the umboes with thick 
obtuse wrinkles converging in the middle; posterior 
side with an oblique elevated angle; postangular 
area flattened with a slight groove in the middle; 

dorsal margin depressed, sloped; anterior side 
very short ; umboes prominent, tumid, angular. 
Anim. s. vert. 
Wagner. 
g 
Lamarck. 
Unio pectinata, 
Hab, Bolivia. 
Another species, to be described under the name of 
Castalia cordata, has been mixed up with this; but 
whatever doubt may be entertained as to which is the 
true C. ambigua, there can be none respecting the 
distinction between the two species. The ribs are 
much sharper in the young state of the shell. 
Species 2. (Mus. 

?) (Copied. ) 
CASTALIA RETUSA.—Cas. testd crass, subtrigond pon- 
derosd, concentrice sulcato-striata ; prope wmbones 
rugis paucis subradiantibus wunpressd ;  latere 
postico oblongo, tumido, obtusé angulato ; latere 
antico breviusculo, margine ventrali rectiusculo. 
RETUSE CasTaLia. Shell thick, 
ponderous, concentrically sulcato-striated; im- 
THE subtrigonal, 
pressed near the umboes with few subradiating 
wrinkles; posterior side oblong, tumid, obtusely 
angular; anterior side rather short, ventral 
margin rather straight. 
Hurk. Castelnau’s Expedition in 
page 75, plate 14, fig. 2. 
South America, 

Species 5. (Mus. Brit.) 
CasTaLIA SCHOMBERGIANA.—Cas. testd trigono-subquad- 
ratd, tenwi, concentrice rugatd, cupred, prope 
umbones rugis divaricatis subradiantibus et sub- 
radiatim inpressa; umbonibus elevatis ; latere 
postico luto, angulo rotundato, ared postangulari 
oblique unisuleato, margine dorsali rotundo elevato, 
margine laterali inter alam et anguli terminum 
excavato ; latere antico breviori, margine dorsali 
declivi ; dentibus tenuibus, laminatis. 
ScHompere’s CastatiA. Shell 
thin, concentrically wrinkled, copper coloured, 
trigonal-subquadrate, 
near the umboes impressed with divergent and 
subradiating wrinkles, umboes elevated; posterior 
side broad, with rounded angle; postangular area 
April, 1869. 
