PILUMNUS. CRUSTACEA. 151 



toes of the forceps black. Inhabits coasts of France. Herbst, 

 pi. 11, fig. 65. 



FAMILY II. ARCUATA. 



Shell arched anteriorly to near the middle of the sides, narrow- 

 ed and truncated posteriorly. 



Gen. 11. PILUMNUS, Leach. Cancer, Lin. 



Exterior antennae setaceous, long, slender, inserted in the in- 

 ternal canthus of the eyes ; third joint of the external feet-jaws 

 almost square, sub trans verse, notched towards the end ; feet of 

 the second, third, fourth, and fifth pairs terminated by simple 

 nails ; shell transverse, truncated posteriorly, with the anterior 

 margin semicircular ; ocular peduncles thicker than the eyes. 



P. hirtellus, Leach. Body and legs bristly ; shell with five teeth 

 on each side ; claws somewhat muricated on the outside. Inha- 

 bits coasts of Devonshire. Perm. Brit. Zool. iv. pi. 6, fig. 1. 



Gen. 12. CANCER, Lin. Lat. 



Exterior antennae short, inserted between the inner canthus of 

 the eye and front, and the intermediate ones in small furrows 

 in the centre ; third joint of the exterior feet-jaws almost 

 square, with a notch at the internal angle of the summit ; 

 anterior feet largest, with the forceps unequal ; shell short, 

 transverse, narrowed posteriorly ; the anterior margin semi- 

 circular, often dentated on the sides, with the lateral angles 

 obtuse ; eyes on a short peduncle. 



C.pagurus, Lin. Shell granulated, with nine folds on each side; front 



with three lobes. European coasts. B Penn. Brit. Zool. iv. pi. 3. 



This species is the Common Crab of Britain. During the summer months it is 



very abundant on all the rocky coasts. At low water they are often found in the 



holes of rocks in pairs, and if the male be taken away, another, it is said, will be 



found in the hole at the next recess of the tide. Crabs are taken in wicker baskets 



resembling mouse traps, sunk in the sea, and baited with garbage. 



C. ceneus, Lin. Shell whitish or pale red, with reddish spots above, 

 and four lobes and a small tooth on each side anteriorly ; front 



almost straight, with two obtuse teeth. Inhabits Indian seas. 



Rvmph. Amb. pi. 11, fig. 4. 



Gen. 13. PIRIMELA, Leach. Cancer, Montagu. 

 Exterior antennae inserted in the internal canthus of the eyes, 

 the intermediate ones in oblique grooves of the hood ; third 

 joint of the exterior feet-jaws square, truncated, and almost 

 notched at its extremity on the internal side ; forceps equal ; 

 the other feet terminated by sharp claws ; shell subtransverse, 

 with the anterior margin semicircular ; orbits with a fissure 

 above and below. 



P. denticulata, Leach. Shell tubercular, smooth, with the anterior 

 sides furnished each with five teeth ; front with three teeth, the 



