in the Museum of the Smithsonian Institution. Ill 



abdomen ; those of the second pair tvo-thiixls as long as the first, 

 slender, cylindrical, and tapering to a filiform extremity. 



This genus is soinewluit allied to Pilummis^ but differs 

 greatly in the character of the orbits and eye-pednncles. 



Aeifloi»!^ laBiibriatii!^, nov. sp. 



Anterior and antero-lateral margins of the carapax ciliated with 

 a fringe of long fine hairs. Carapax covered with a short pubescence, 

 and areolated, the areolets being sufficiently distinct, but not at all 

 protuberant. Angle of the orbit and next tooth of the antero-latei-al 

 margin about equal in size ; the other two teeth veiy small. Sub- 

 hepatic region smooth. Front not prominent ; median sinus slight ; 

 lobes very slightly convex. External maxillipeds hairy ; meros-joint 

 somewhat swollen. Chelipeds somewhat hairy ; hand granulated on 

 the outer side ; fingers short, acuminate, and with granulated longi- 

 tudinal ridges. Ambulatory feet ciliated. 



Dimensions of a male specimen : Length of carapax, 0.21 ; breadth, 

 0.28 inch. 



This little crab resembles Ceratoplax c'diatus in appearance. 

 Cape St. Lucas. J. Xantus. 



Achelous transversals, nov. sp. 



Carapax broad ; regions only slightly protuberant ; ridges distinct, 

 granulated ; branchial ridge sinuous, but only slightly convex, curv- 

 ing forward even less than in A. Gibhesii and scarcely more than in 

 Callinectes^ but nevertheless forming an angle near the base of the 

 lateral spine. The oblique meso-branchial lobes are distinct. The 

 lateral spine is long, as long as the space occupied by the four or five 

 teeth in fi'ont of it. The other antero-lateral teeth are pretty strong, 

 equal, and have a granulated surface. Front nearly as in A, pana- 

 mensis described below, but with the teeth somewhat more pointed. 

 Chelipeds rather short ; meros fo\ir-toothed in front. Meros of the 

 posterior pair of feet with a spiniform tooth at inferior extremity. 



Dimensions of a male : Length of carapax, 0.39 ; breadth., 0.85 

 inch. 



Of this species I have seen only one specimen, which is iin- 



NOVEMBER, 1871. 8 Ann. Lyc. Nat. Hist. Vol. X. 



