CRUSTACEA— MALACOSTRAC A. 395 



margins notched, forming a regular curve with the frontal margin, 

 which is also marked by several notches; postero-lateral margins 

 straight and rapidly converging ; posterior margin short ; regions 

 of the cephalothorax faintly outlined. Eocenic-Recent. (Fig. 

 1694.) 



43. C. fissus Rathbun. Miocenic. 

 Anterior angle of each lateral tooth scarcely projecting sideways 



beyond the tooth immediately in front of it; teeth subtruncate, 

 separated by V-shaped notches and long closed fissures, eight on 

 each side ; postero-lateral borders formed by thick granulated line, 

 which is continued across the posterior margin. Length to width, 

 as I to 1.45; cardiac region more distinctly divided in the middle 

 into two elevations. 



Etchegoin (Lower Miocenic) formation of California. 



XXIV. Callinectes Stimpson. 

 Carapace twice as wide as long; antero-lateral margin forming 

 with the front a regular curve, and marked by nine strong spines, 

 the last a pronounced lateral spine ; chelae with long narrow toothed 

 claws; posterior pair of pereiopods with last joint (dactylus) 

 flattened into a paddle and used in swimming; second, third and 

 fourth pair of legs for walking; first abdominal segment entirely 

 concealed, first and second with appendages ; in female second, 

 third, fourth and fifth segments bear appendages. Pleistocenic- 

 Recent. 



44. C. sapidus M. J. Rathbun. Pleistocenic-Recent. 

 Carapace moderately convex, with granules of medium size, 



scattered and faintly marked on anterior half of carapace, but 

 crowded on the inner branchial and cardiac regions ; two frontal 

 or interantennal teeth, triangular acute, and with faint indications 

 of two others on their oblique inner margins; lateral spines in 

 males from 3 to 4 times the length of preceding tooth; merus of 

 first pair of pereiopods with three sharp oblique spines on its 

 anterior edge; chelae with 12 to 14 unequal teeth on each finger. 

 Pleistocenic of Sankaty Head, Mass., and of New Jersey, and 

 Alaryland; Recent: Cape Cod to Florida. 



