390 REPORT OF NEW JERSEY STATE MUSEUM. 



illipeds not completely closing buccal cavern, and with palpus not 

 concealed by merus joint. Verges of miale exserted from bases 

 of fifth pair of legs. 



These are among the best known of their tribe. They are 

 largely characterized by the unusual formed and large chelipeds, 

 these being furnished with cockscomil>like crests on the upper 

 edges of the hands, and which in flexion are presssed tightly 

 against the lower surface of the carapace like a shield. This 

 arrangement is credited to protect from attack any morsels of 

 food they may be eating. These crabs mostly live on sandy 

 shores, into which they burrow. One genus represented on our 

 shores. 



Genus CALAPPA Fabricius. 



The Box Crabs. 



Calappa Fabricius, Entomol. Syst. Siippl., 1793, pp. 309, 415. Type Cancer 

 calappa Linnaeus, virtually first species and thus by tautonomy. (To 

 avoid the latter Fabricius names it Calappa fornicata.) 



Carapace strongly convex, rounded in front, much broadened 

 behind by pair of clypeiform expansions or wings, beneath which 

 ambulatory legs are concealed in flexion. Front small, somewhat 

 triangular, projecting little or not at all beyond level of orbits, 

 bilobed. Orbits small, circular. Eye-stalks short and thick. 

 Antennul^e nearly vertical. Basal joint of antennae very broad 

 and filling wide hiatus at inner angle of orbit. Outer maxillipeds 

 not meeting, but leaving exposed mandibles and, in front of 

 them, lamellar processes from first pair of maxillipeds. These 

 processes form bases of two channels separated by deep vertical 

 septum extending to antennulary fossae. Chelipeds very large, 

 and in flexion fitting closely front half of carapace, forming a 

 sort of buckler. Merus externally and near distal end with trans- 

 verse wing-like expansion. Hand strongly compressed, its upper 

 border forming high dentate crest. Chelipeds equal except for 

 fingers, which on one hand have, outside near base, a stout pro- 



