168 Prof. F. M‘Coy on the Classification of 
Basinotopus Lamarckii (Desm. sp.). 
Syn. Inachus Lamarckii (Desm.). 
Carapace broad ovate, very slightly longer than wide, gibbous ; 
rostrum short triangular, deeply channeled, bent downwards 
and with a small tooth on each side, a strong rough tubercle 
on each side of the base forming the inner angle of the orbits, 
another tubercle forms the outer angle, and from this to the 
level of the base of the cardiac region the margin bears four 
strong spinous tubercles ; the gastric region extends half the 
length of the carapace, is strongly trilobed, the middle portion 
(corresponding to the so-called genital region of many crabs) 
tumid, subpentagonal, the pointed end extending to the level 
of the orbits; it bears one large rounded tubercle at each side 
of its base, and several irregular smaller ones between those 
and its apex; the lateral portions of the gastric region are less 
prominent and have an oblique ridge formed by the confluence 
of two or three tubercles parallel with the converging sides of 
the middle portion ; below those near the nuchal * furrow is a 
large cleft tubercle, and sometimes between those and the orbit 
two or three small granules; a slight hollow separates the 
gastric from the small square hepatic regions, which correspond 
on each side to the two anterior marginal spines, each bears 
one tubercle in its middle ; pterygostomian regions very tumid, 
mamumillated ; branchial regions very large, each divided about 
the middle by a strong, prominent transverse ridge extending 
from the cardiac region to the fourth (or last) great marginal 
spine ; the anterior edge of this ridge is plicated, and the space 
between it and the nuchal furrow bears two tubercles, the 
anterior smallest ; the large, peculiar basal space behind these 
ridges is continuous from side to side behmd the mtestinal 
region ; it is closely pitted and rough with minute wrinkles ; 
genital region forming a narrow transverse tuberculated ridge, 
its length being only one-fourth of its width, which equals that 
of the cardiac region, which is very gibbous, rotundato-qua- 
drate, and bearing a large hemispherical tubercle on each side ; 
intestinal region forming only a small mucro, imperfectly se- 
parated from the cardiac, and not extending more than half- 
way into the rough basal space towards the posterior margin ; 
abdomen of six jomts, in the male narrow, with nearly parallel 
sides, obscurely trilobed longitudinally, the first jot very 
* T use this term to designate that most important and constant of all the 
furrows of the carapace—namely that which runs transversely across the 
back, forming the posterior boundary of the gastric and anterior hepatic re- 
gions ; it is especially stvong, and frequently the only furrow, in the carapace 
of the Macrwra, and corresponds on the back to the line of separation 
between the cephalic and thoracic segments beneath—the neck as it were, 
whence the name. 
