CRUSTACEA. 123 



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 

 pn each side to the two anterior marginal spines, each bears 

 one tubercle in its middle ; pterygostomian regions very tumid, 

 mammillated ; 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 behind the intestinal 

 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 joints, in the male narrow, with nearly parallel 

 sides, obscurely trilobed longitudinally, the first joint very 



* I 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 strong, and frequently the only furrow, in the carapace 

 of the Macritra, 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. 



