24G NKW genera and species of crabs — RATHIUIN. 



Tbis may ho i«leiitical with a short- lingered specime i lioiii the west 

 coast of Low«'i' California, which Lockini^toM (h)ul)tfiilly refers to stcno- 



Gelasiinus coloradensis. 



Carapace very eoiivex, regions protnlxMant, smooth; there is a h)U- 

 gitudinal groo\'e crossing the l)rancliial region, and tliis groov*' opposite 

 tlie posterior margin «tf the gastri<' region wich'ns into a (h'epi»it from 

 wliich line irregiihir grooves radiate; ccrxical sntnrc deep, with a ]>it 

 near tiie frontal margin. Front broad. Posterior or np|»er edge of the 

 snperior (nbital lK)ri1er cnrxing forwar<l and oidward, with snuutth mar- 

 gin; iinterior or lower edge denticnlate, carving rapidly downward near 

 the base oi' the oenlar jtednncle. then gradnally ronnding ni»ward to 

 Join the posterior margin at a little distance Irom the antero-latera-1 

 angle of the carapace, which is acnte and i»oiids forward. The 

 lateral bonier is maiked by a shar]»ly njitnrned and linely denticu- 

 late margin which slo]>es inward anteriorly, so that the carapace is 

 much narrower at the anterolateral angles than posterior to them ; 

 and the posterior portion of the lateral margin is stumgly incurved 

 and terminates opjjosite the cardiac region. The inferior orbital 

 border is marked by abont twenty-fonr distinct tuberch\s. The eye- 

 stalks are slender and do not nearly till tiie orbit. The jngal region is 

 covered with depiessed tnberch's. Male abdomen broad, second seg- 

 ment mnch shorter than the first, sixth segment wider than the tilth; 

 appen<lages slender. Ischinm of outer maxdlipeds wide and smooth; 

 merns short. The left cheliped (the larger in the one specimen at hand) 

 is very hnig; merns as long as the carapace, rngose, inner margin lin«'ly 

 tubercnlate; carpus also rugose, inner margin tnbercnhite, the tuber- 

 cles coarser t<^) wards the proxinml end ; inner snrfaee with a tubereu- 

 late ridge; ]>alin with the npi»er i>ortion tnrncd abrnptl.N' inwai«l almost 

 atu right angle but wilhont a shari) ridge; the upper surface is depressed 

 and obscurely tuberculat*', the tubercles beconnng large and coarse 

 near the union witli the outer surface, which is crowded with granules 

 Avliich are smaller toward the tnbeiculate lower edge; ther«' is a deep 

 depression lietween tlu' pabn and poUex; the inner surface of the 

 l>alm has a row of coarse tubercles extending from the lower maigin 

 obhcpu'ly upward and joining at right angh's fh«' row extending to tlie 

 upper surface. Tlu^ row of denticles or tnberi les on the inner margin 

 of the pollex is continued i)arallel to the base of the dactyl, and between 

 this row and the dactyl ther*' is an additional row; the irregidar de- 

 pression anterior to the oblique row is smooth and shining to the naked 

 eye, but with the lens tine scattered granules may be seen near the 

 gape of the lingers and continued on the p(»Mex; pollex nearly twice as 

 long as palm, ahnost straight, linely denticulate on the outer and inner 

 margins of the prehensileedge, with a rowof irregular tubercles between ; 

 distinctly two toothed at the upturned extrennty; dactyl overreaching 



