238 PROCEEDINGS OF THE ACADEMY OF 



CATALOGUE OF CRUSTACEA FROM THE ISTHMUS OF PANAMA. 

 COLLECTED BY J. A. McNEIL. 



BY T. HALE STREETS. 



BRACHYURA. 



MAIOIDEA. 

 Family MAIIDEA. 

 Subfamily Pisinae. 

 Omalacantlia, nov. gen. 



Carapax pyriform as in Pisa. Orbit complete above and below, 

 oval, superior border armed with a triangular tooth. Eye verj' 

 small; peduncle short. Rostrum well developed, bifurcated nearly 

 to base, horns divergent, apices convergent ; praeorbital tooth flat- 

 tened, obtuse; external anteunai not hidden by rostrum, but com- 

 pletely exposed, on same level as rostrum ; first and second arti- 

 cles broad, flattened, clubbed at distal extremit}'. 



This genus is very closely allied to that little known genus, 

 Micropli7-y^^^ M. Edw. It is readily distinguished from Microphryii 

 hy its greater triangular form (not being broader than long); by 

 the broad, club-shaped articles of external antenuii? (in llicrophrya 

 they are cylindrical), and by the antero-lateral border of carapax 

 beiiig less inflated. 



Omalacantha Mrsuta, nov. 5p. 



Carapax triangular, convex, tuberculated, pilose ; hairs hooked 

 at extremity; prominent spine projecting from junction of antero- 

 lateral with postero-lateral border; another smaller spine below, 

 and in front of this on branchial region ; spine on hepatic region 

 below and behind external angle of orbit; one on side of branchial 

 region, near the groove separating it from hepatic; row of five 

 small tubercles on inferior border of hepatic region ; on gastric 

 region tubercles arranged in the form of the letter T; an arcuate 

 row of four tubercles on intestinal region ; another single one 

 below these at posterior extremity of same region. Longitudinal 

 row of hairs on horn of rostrum, and continuing on lateral portion 



' For description, see ''Zoologie Expedition dans rAinerique du Sud, 

 p;ir Castlenau." 



[December 5, 



