Dr. P. L. Sclater on Animals from Madagascar. 297 



migerous process of the third joint is rounded and thickened upon the 

 outside, straight, thin, and ciliated upon the inner, and obtuse at 

 the apex. The rostrum reaches to the extremity of the penultimate 

 joint of the peduncle of the external antennse, rounded at the ex- 

 tremity, dorsally concave, the margins fringed within and above 

 the actual edge with a rim of short, blunt denticles. The ocular 

 orbit is deeply excavate, and armed posteriorly near the centre by a 

 small denticle, and at the infero-lateral extremity by a short, sharp, 

 curved, and anteriorly directed strong tooth. The lateral walls of 

 the cephalon are thickly covered with numerous, subequally distant, 

 short, spinous protuberances, which gradually lessen in importance 

 towards the dorsal surface of the carapace, which is perfectly smooth, 

 except for the well-defined fissure that distinguishes the anterior 

 portion of the carapace from the posterior — the demarcation between 

 the antennal and mandibular somites. The first or large chelate 

 pair of pereiopoda are subequal in size, but differ in form from those 

 of every other species of the genus with which I am acquainted, and 

 resemble more in general aspect those of the genus Homarus. The 

 dactylos is curved inwards, and tipped with a sharp unguis ; the 

 dactyloid process of the propodos is similarly formed, and meets the 

 dactylos only at or near the apex ; the approximating edges, how- 

 ever, are armed with a few small and one large tubercle opposite to 

 corresponding ones. The inferior and external margin of the pro- 

 podos, from the extremity of the dactyloid process to the carpal ar- 

 ticulation, is convex, and longer than that of the intero-superior 

 margin of the propodos and dactylos together. The carpus is armed 

 with three blunt and one sharp anteriorly directed teeth upon the 

 inner edge, and two sharp strong teeth upon the under surface. 

 The meros is furnished with two rows of teeth, that converge toge- 

 ther towards the ischium upon the inner surface. The other pereio- 

 poda have little to attract attention. The second somite of the pleon 

 has a tuberculous ridge just above the lateral margin. The inner 

 scale of the posterior pair of pleopoda is furnished with a central 

 row of short, sharp teeth ; and the telson is armed with similar teeth, 

 of which there are a few in the mediau line and others in two late- 

 ral obsolete rows. 



The specimen from which the description is taken is a male. Of 

 all the species of this genus, this form approximates the nearest to 

 its marine allies, in the appearance of the great chelate pereiopoda, 

 of any that we are acquainted with. The generally close resemblance 

 of the several species of this genus is certainly very remarkable, 

 when we take into consideration the vast geographical distribution 

 that it has — larger, perhaps, than that of any genus of Crustacea 

 that is not of marine habits. Species have been taken in the frozen 

 waters of North American rivers, in the hot latitudes of Chili, in 

 temperate Europe and Tasmania, and now from the African island 

 of Madagascar. We do not know of any having yet been recorded 

 from the inland rivers of that continent. 



