CUCULLAA. 
Genus CUCULLAA, Lamarck. 
Testa bimusculosa, bivalvis, subequivalvis, trapeziformis, 
ventricosa, umbonibus distantibus, area ligamenti 
lata, complanatd, separatis. Impressio muscularis 
postica in laminam septiformem producta. Cardo 
linearis, rectus, dentibus parvis subdivergentibus 
instructus ; utraque extremilate costis duabus ad 
quinque transverse parallelis.  Ligamentum ex- 
ternum, super aream depositum. 
Shell bimuscular, bivalve, nearly equivalve, trapezi- 
form, ventricose, umbones distant, separated by a 
broad, flat, igamental area. Posterior muscular 
impression produced into a septiform lamina. 
Hinge linear, straight, set with small subdivergent 
teeth, with two to five transversely parallel ribs at 
each end. Ligament external, deposited upcn the 
area. 
The curious auricle formed by the produced edge of 
the muscular impression, and the peculiarly disposed 
teeth and terminal ribs on the linear hinge, render this 
avery remarkable genus. After patient examination 
of a number of specimens I have arrived at the con- 
clusion that they may be divided into three species; 
two, long known and confounded under the names of 
Cucullea concamerata and C. auriculifera, of both 
which the stated locality is the “Isle of France,” 
and a third more recently distinguished by Jonas 
under the name C. granulosa, which is said to be 
from China. 
Species 1. (Fig. a, 6, Mus. Sowb.) 
CucuLL@#A CoNcAMERATA. Cuc. testd trapezorded, crassa, 
ventricosissimad, oblonga, costellis complanatis 
minutissimé decussatis radiata, 
flammulisque variegatd, versus marginem ventralem 
fusco-purpurascenti, intus albidd, posticé purpurea ; 
latere postico acuté angulato, post angulum late- 
raliter complanato, etiam subconcavo, ad cardinem 
cuneato, ad marginem ventralem acuminatim pro- 
ducto ; margine ventrali recto; latere antico sub- 
albidd, maculis 

quadrato, breviusculo ; dentibus centralibus minutis 
wregularibus striatis, dentibus terminalibus posticis 
tribus, anticis duobus parallelis ; auriculd septi- 
formi interna 
elevatissimis, valdé angulosis. 
THE CHAMBERED CucuLL@a. Shell trapezoidal, thick, 
very ventricose, oblong, rayed with flattened very 
minutely decussated riblets, whitish, variegated 
with spots and little flames, brown-purplish to- 
wards the ventral margin, whitish within, purple 
posteriorly ; posterior side acutely angular, late- 
rally flattened behind the angle, even rather con- 
cave, cuneate at the hinge, acuminately produced 
at the ventral margin; ventral margin straight; 
anterior side subquadrate, rather short; central 
musculari umbonibus 
mediocri ; 
teeth minute, irregular, striated, posterior ter- 
minal teeth three, anterior two, parallel; internal 
septiform auricle of middle size; umbones very 
elevated, very angular. 
Martini. Chemn. Conch. 7, pl. 5, pl. 53, f. 526, 527. 
Arca cucullus. Gmel. 
Arca cucullata, Chemn. 
Cucullea auriculifera (pars.) Lamarck. 
Hab. Isle of France. 
The probabilities, on the whole, are favourable to 
the shell we have here figured and described being the 
one named by Martini. It is distinguished by its 
rather straight ventral margin, its slightly concave 
posterior lateral margin, and by its more variegated 
painting towards the umbones. The terminal teeth 
are more straight and bifid. 

Species 2. (Fig. a, b, Mus. Sowerby.) 
CucuULLHA GRANULOSA. Cuc. testd subquadrata, tenui- 
usculd, ventricosa, alta, costellis rotundatis decus- 
satim granulatis subduplicatis et interstitiis minute 
foveolatis radiata, albida, maculis fuscis ante 
angulum parvis, post angulum magnis, angulatis 
picta ; ints alba, versts marginem purpurea, super 
auriculam unifasciata ; latere postico obtusé angu- 
August, 1869. 
