584 I'HOCEEDINCS OF THE NATIONAL MUSE I'M. 



ambulatory legs are, however, very distinct. They are shorter than in 

 M. spinimamts. The nieral Joints are armed on the upper or anterior 

 margin with spiniform teeth, as in that species; the tubercles of the 

 upi)er surface of the last pair are more depressed. The carpal and 

 propodal joints are ornamented with lobate crests, of which there are 

 three on the carpal joints of the first, second, and third pairs, and 

 two on the propodal joints and on tlie car])al joint of the fourth i)air. 

 The middle crest of the carpal joints (tlie anterior crest in the last 

 pair) is most prominent, and is composed of three rounded lobes, the 

 interspaces as wide as the lobes. Ambulatory legs hairy, the dactyli 

 densely so. 



Abdomen of male with the first three segments tuberculous; anterior 

 margin of each segment, including the coalesced segments, marked by 

 a transverse band of pubescence. Posterior half of sternum tubercu- 

 lous; anterior half punctate or pitted. 



Dimensions. — Male, type: Length, 17 mm.; width, 25.6 mm. Female 

 with eggs, station 2812: Length, 8.5 mm.; width, 12.3 mm. 



Type. — No. 21580, U.S.N.M. One male, from Panama Bay, 33 fath- 

 oms, station 2796; 



Additio)ial specimens. — Panama Bay, 5^ fathoms, station 2805, two 

 small males; oft" Hood Island, Gala]>agos, 20 fathoms, one female; oft' 

 Cape St. Lucas, 31 fathoms, station 2829, one male. 



LIP^^STHESIUS, new genus. 

 (AeiTfo), to be wanting; ai60Tj6i<;, perception by feeling.) 



Allied to Glyptoxantlius, Medfeus, and Carpoporus. Basal antennal 

 joint excluded from the orbit; Jiayellum and peduncular joints ic anting ; 

 antero-lateral margin of the carapace terminating at the angle of the buccal 

 cavity. 



Carapace in shape resembling Glyptoxanth us ; that is, the antero-lateral 

 margin is arcuate, the postero lateral is deeply concave, the anterior 

 half of the carapace is very convex longitudinally, the posterior half 

 is llatteued. The antero-lateral margin, however, is thinner than in 

 Glyptoxanthus, and runs obliquely downward to the angle of the buccal 

 cavity, as in Med(vus. Front dellexed, forming a projecting hood over 

 the anten]iula\ Orbits circular. Basal antennal joint less advanced 

 than the orbital angle; its anterior margin articulates with the lower 

 corner of the front, as does also the inner corner of the lower orbital mar- 

 gin (Plate XLII, fig. 5). The antenuif proper, including the peduncular 

 joints and the llagellum. are absent. Only tbe flat lower surface of the 

 basal joint is exposed to view, and there is no .socket to hold an antenna. 

 Epistome with a deep transverse invagination through its entire width. 

 Abdomen of male with tlie third, fourth, and fifth segments anchylosed. 

 Chelipeds concave on their inner side to fit closely against the cara- 

 pace. Last pair of ambulatory legs fitting into the posterolateral sinus 

 of the carapace. 



