156 BULLETIN OF THE 



Family CORYSTID^. 



TRACHYCARCIinJS, gen. nov. 



Carapace pentagonal, moderately convex, lateral margins long, nearly straight 

 toothed. Front narrow, produced, three-toothed. Orbits large, with forward 

 aspect, imperfect, with two hiatuses above, one below, and one at the inner 

 angle ; lower wall formed chiefly by the carapace. Anterior margin of buccal 

 cavity not distinctly defined, epistome short, ridges of the endostome devel- 

 oped. Sternum long and rather narrow. Abdomen of male narrow and five- 

 jointed, the third, fourth, and fifth segments consolidated. Eyestalks very 

 small, retractile within the orbits. Antennules longitudinally folded. The 

 antennae lie in the inner hiatus of the orbit ; their basal segment is but 

 slightly enlarged, not filling the hiatus at the inner angle of the orbit, nor 

 attaining to the front, subcylindrical, unarmed, imperfectly fused with the 

 carapace ; the second segment is longer and slenderer than the first, the third 

 segment about equal to the second in length, but slenderer ; all these segments 

 are furnished with long and coarse setae ; the whole antenna is less than one 

 half as long as the carapace. The ischium of the outer maxillipeds is produced 

 at its antero-internal angle ; the merus of the same appendages is rounded at 

 the antero-external angle, obliquely truncated but not emarginated at the 

 antero-internal angle, where it articulates with the following segment. Legs 

 of moderate length. Right and left chelipeds very unequally developed in the 

 male. Dactyli of ambulatory legs styliform, straight, slender, longer than the 

 penultimate segments. 



The pentagonal shape of the carapace recalls the genus Telmessus White. 

 But in Telmessus the front is divided by a median notch, the orbit is much 

 more complete, the basal segment of the antenna sending off an external pro- 

 cess that completely fills the hiatus at the inner angle of the orbit. In the 

 structure of the orbit and antennae, and in the shape of the merus of the outer 

 maxillipeds, Trachycarcinus is much like Hypopeltarium Miers {Peltarion 

 Jacq.). 



Trachycarcinus corallinus, sp. no v. 



Carapace irregularly pentagonal, clothed with a dark brown pubescence, and 

 bearing flattened tubercules of ivory whiteness arranged in groups, as follows : 

 two anterior lateral and one posterior median, on the gastric region ; four, dis- 

 posed in two pairs, on the cardiac region; five or six on each branchial region; 

 and one, of a crescentic shape, on each hepatic region. Each group of tubercles 

 resembles the crown of a complex molar tooth whose cusps have been worn 

 down to a common level. Front tridentate, the median tooth twice as long as 

 the lateral. Walls of the orbit furnished with four teeth separated by deep 

 hiatuses ; these teeth are a pre-ocular, median superior, post-ocular, and sub- 



