MUSEUM OF COMPARATIVE ZOOLOGY. 127 



found. Carapax similar to that of P. Riisei, except that there is a spini- 

 form tubercle, curving backward at the tip, on the gastric region, and that 

 the rostrum is smaller and more pointed. The two marginal lamellae of 

 the basal joint of the external antennae are strongly prominent, joining 

 each other in front, and curving outward at the posterior extremity On 

 the ischium-joint of the external maxillipeds there is a smooth longitu- 

 dinal channel, denned exteriorly by a ciliated ridge. On either side of 

 the buccai area there are four laminiform crests ; one at the antero-exterior 

 angle of the area, one on the hepatic, and two on the pterygostomian 

 region. The sternum, where not covered by the abdomen, and the bases 

 of all the feet, are ornamented with cavities, the surface of each joint being 

 concave and surrounded by a laminiform expansion. 



Dimensions of the female specimen : Length of carapax, 0.44 ; breadth, 

 0.37 inch. 



It was taken at the depth of 21 fathoms, off Tennessee Reef, on the 7th 

 of May, 1869. 



Podonema hypoglypha nov. sp. 



The following description is that of a male. Gastric, cardiac, and 

 branchial protuberances low and rounded. Rostrum slightly curved up- 

 ward, and triangular in outline when seen from in front and below, but 

 with the lateral expansions well developed. The basal joint of the ex- 

 ternal antennae is greatly elongated, and the laminiform expansions of the 

 margins slight. Hepatic tooth and pterygostomian ridges moderately 

 developed. Sternum with deep and broad channels separating the seg- 

 ments, which have each a corresponding flattened ridge as broad as the 

 channel. 



Dimensions of a male specimen : Length of carapax, 0.63 ; breadth, 

 0.48 inch. 



It differs from P. Puisei in the shape of the rostrum, and from both 

 Pdisei and lamelligera in the elongated basal joint of the external an- 

 tennae. 



No female specimen occurs in the collection. 

 Key West, in 4 to 5 fathoms. 

 S. W. of Loggerhead Key, in 9 fathoms. 



Family ACANTHONYCHIDAE. 



In this group the eye is short, in some genera scarcely movable, and in 

 others somewhat retractile, or rather capable of being moved in a horizon- 

 tal plane. There are no true orbits, but in many genera the eye lies 

 beneath the expanded orbital margin of the carapax, which has frequently 

 two teeth, one before and one behind the position of the eye. The eye 



