128 CRUSTACEA. 



tail-flaps) 2 inches 2 lines ; length of hand 1 inch 3 lines, of 

 carpus 4 lines, width of hand at middle S^ lines. 



This is most allied to the only other liassic species which I am 

 aware of, namely the E. Hartmanni of Herman von Meyer (see 

 his " Beitrage zu Eryon '' in the 18th vol. of the Nova Acta Acad. 

 Cses. Leop. Carol. &c.), from which it differs in its much shorter 

 abdomen, a character which approximates it to the otherwise dis- 

 similar E. subpentagonus (Miinst.) and E. arctiformis (Schlot.) 

 of the Kelheim and Solenhofen lithographic slates. In all the 

 species described by Von Meyer and Miinster the hand and car- 

 pus taken together equal or exceed the middle of the carapace in 

 length ; this species is therefore most remarkably distinguished 

 by the comparative shortness of its chelae as well as their greater 

 robustness. 



Rare in the lias of Barrow-on-Soar. 



{Col. University of Cambridge.) 



Archceocai^ahus (M'Coy), n. g. 



Etym. ap')(alo(;, antiquus, and Kapa^o^;, Aristotle's name for the 

 Palinurus or spiny lobster. 



Gen. Char. External antenna very thick and long, the setae of 

 very short fimbriated joints ; first pair of feet much thicker 

 than the others, the extremity of the penultimate joint dilated 

 on its inner side to a broad, subtruncate, subcompressed hancl 

 as wide as the length of the curved terminal joint which is 

 inflexed on it ; four posterior pairs of legs slender, compressed ; 

 carapace semicylindrical, obtusely rounded above ; nuchal fur- 

 row very wide and deep, extending with a gentle backward 

 curve across the carapace in front of the middle ; cephalic por- 



Diagram of Archcsocarabus. 

 a. Portion of one of the outer antennae. 



tion depressed, front wide, subtruncate toothed, the lateral 

 angles produced into large, flattened, slightly recurved spines 

 over the eyes, shell below the orbits prolonged forwards into a 

 thick spine; crust excessively thin and fragile, covered with 



