52 CRUSTACEA. 



in both sexes; the shell ovoid, widely truncated, without any projec- 

 tion like a rostrum, and flattened. 



As remarked by Desmarest, we may observe on each side and 

 above the origin of the claws an oblique fissure resembling a button- 

 hole, longitudinally intersected by a diaphragm, ciliated, like itself, 

 on the margin that communicates with the branchioe, and affording 

 an issue to the water that bathes them. 



Three species are found in the Mediterranean(l); the others 



inhabit Oriental seas, and one of them B. quadridens^ Fabr., 



Herbst., X, 70, is also obtained there in a fossil state. 



There, the shell is sometimes nearly orbicular, or globular, and 



sometimes arcuated anteriorly and narrowed posteriorly, and den- 



tated or spinous on the sides. The eyes are situated near the middle 



of the front and placed on short pedicles. 



Dromia, Fab. 



The four posterior feet inserted in the back, and terminated by a 

 double hook; the shell suborbicular or nearly globular, convex and 

 woolly, or very hairy. 



With their hind feet they seize upon Alcyonii, shells, and other 

 bodies, beneath which they shelter themselves, transporting them 

 wherever they go. 



The most common species, — Cancer dormia, L., Rumph., 

 Mus., XI, 1; Herbst., XVIII, 103, is found in every sea, that of 

 the North excepted. It is covered with a brown down, and has 

 five teeth on each lateral margin and three in front. The fin- 

 gers are stout, deeply dentated on the two edges, and partly 

 rose-coloured. Some authors say that it is venomous. 



The Death's Head, — Cancer caput mortuum^ L. ; Dormia clype- 

 ata, Act. Ilafn., 1802, is smaller, more convex, almost globular, 

 with three teeth on each side in its anterior margin, and has a 

 short front, emarginate in the middle and laterally sinuous. It 

 is found on the coast of Barbary(2). 



Dyxomene, Lat. 



The tAvo posterior feet much smaller than the others, alone dorsal, 

 and apparently unarmed; the shell widened, and nearly resembling 

 a reversed heart truncated posteriorly, like that of the last Quadri- 



(1) Dorippe lanata; Cancer hniatus, L.; Desmar., Consider., XVII, 2; — D. 

 affinis, Id.; Herbst., XI, 67; — Cancermascarone, Herbst., XI, 68. 



(2) For the other species see Desman, Comid. Gen. sur la Classe des Cru/st., 

 p. 136, et seq. 



