26 CRUSTACEA, 



elongated, salient and composed of many joints, but very hairy as 

 well as the claws; the latter strong, and with compressed hands. 

 The third joint of the foot-jaws sensibly narrowed above, resembling 

 an obtuse or rounded tooth; conical tarsi, and the ocular pedicles 

 of the ordinary size. The tail is longer than in the preceding Crus- 

 tacea. 



Two species have been described(l). One from the coast of 

 England, of a sub-orbicular form, and the other from that of 

 France, Mediterranean as well as Oceanic. The 



Thia, Leach, 



Approaches Atelecyclus in the lateral antennae, in the direction of 

 the fossulse in which the intermediaries are placed, in the form of 

 the third joint of the external foot-jaws, and in the sub-orbicular 

 shell; but the eyes, together with the pedicles, are extremely small 

 and scarcely salient. The tarsi are strongly compressed and sub- 

 elliptical. The front is arcuated, rounded, and without any marked 

 dentations. The pectoral space between the feet is very narrow, 

 and of the same breadth throughout. The claws are much weaker 

 in proportion. The shell is smooth, and in some respects the Thiae 

 approach the Leucosiee and the Corysies. 



The type(2) of this subgenus, whose habitat was unknown, 

 has been discovered by Milne Edwards in the sandy shores of 

 the Mediterranean, near Naples. Risso — Journ. de Phys., 1822, 

 p. 251, — described a second, dedicated to M. de Blainville, 

 which he found in the river at Nice. The 



MuRSiA, Leach(3), 



Of which but a single species is known, and which is peculiar to 

 that part of the Ocean which bounds the southern extremity of Afri- 

 ca, approaches the Matutae and several Portuni, in the long spine 

 with which each side of the shell is armed posteriorly; it also 

 approximates to the true Crabs in the form of the shell and of the 

 external foot-jaws, with this difference, that their third joint forms 

 an elongated square, narrowed and obliquely truncated at its supe- 

 rior extremity; but, as in the Calappae and Hepati, the hands are 

 strongly compressed above, having a sharp and dentated edge, re- 

 sembling a crest(4). 



(1) See Consid. Gener, sur laClasse des Crust, Desmar., p. 88, 89. 



(2) Thiapolita, Leach, Zool. Miscell. ciii. 



(3) This name must be changed to avoid confounding the division with that of 

 Nursia, anotlier subgenus. 



(4) Desmarest, Consid. Gener., &.c., IX, 3- 



