128 BULLETIN OF THE 



is, however, never concealed by these expansions. The carapax is gen- 

 erally flattened, angular, and naked, instead of subpyriform and spinous 

 as in the majority of Maioids, The feet are usually short. 



It is necessary to reject the name Periceridae, which was applied to this 

 group by Dana, for in the genus Pericera the eyes are completely retractile, 

 as stated on a previous page. The genus Acanthonyx seems the most 

 typical of the group, and from this is taken the name adopted above. 



Subfamily EPIALTINAE. 



Epialtus longirostris Stm. 

 Epialtus longirostris Stimpson, Notes on N. American Crust., p. 71. 

 Found at Key West, in from 2 to 5 fathoms. 



Epialtus aflinis Stm. 

 Epialtus affinis Stimpson, Notes on N. American Crust, p. 3. 

 Found on the Reef at Cruz del Padre, Cuba. 



Mocosoa nov. gen. 



Carapax subpentagonal, tumid ; rostrum subtriangular, entire, obtuse, 

 excavated below ; eyes large, immovable. External antennae concealed 

 beneath the rostrum and not reaching to its tip ; basal joint triangular, 

 unarmed in front. External maxillipeds very broad ; meros-joint particu- 

 larly short and broad, with the outer angle much projecting outward, and 

 the inner one a right angle, not at all notched for the reception of the 

 palpus. 



This genus differs from Epialtus in its immovable eyes, which resemble 

 those of Huenia. From Huenia it differs in the character of the rostrum. 

 The name adopted for the genus is that of one of the Florida Caciques 

 encountered by De Soto in his march. 



Mocosoa crebripunctata nov. sp. 



Upper surface of carapax everywhere uniformly punctate, the minute 

 pits being equal in size and wider than the interspaces. Carapax naked 

 and protuberant, there being two prominences between the eyes, three on 

 the gastric region, one large one on the cardiac, and three on each bran- 

 chial region. Of the three branchial protuberances one is situated at the 

 middle of the region, and two on the outer margin, the posterior one 

 being smallest and bearing a minute blunt spine. Feet short and armed 

 with a few short, blunt spines, chiefly on the meros-joint. 



Body of a strawberry color ; upper surface of carapax iridescent. 



