58 



ON THE BRACHYUROUS DECAPODS OF THE CAPE. 



Feet, first pair tliicker tlian the rest, and having the digits serrulated on the inside ; the second 

 pair longer than the first, and, as well as the three posterior pair, it is furnished with a 

 subcheliform penultimate joint, which is truncated at the apex, and unidentated. 



Abdomen of male has seven segments. 



This groupe is in the family Mithracidce exactly what Acanthonyx is in the family Epial- 

 tidcB. Both are analogous groupes in contiguous famihes ; but whether they ought to be con- 

 sidered as sub-genera, or only sections of sub-genera, remains yet to be discovered. 



Sp. 4. ( ) Dehaanius acantliopus, n. s. fX IJi 



Descr. Dehaanius testa glabra, margine lateral! antice tridentato, dente medio majore, clypeo 

 fossula inter dentes duos medios majores longitndinali. 



Note. Carapace pyriform and without hair, having the digestive, cardiac, and branchial 

 regions distinct. Anterior lateral margin tridentate, the middle tooth being much the largest. 

 Clypeus short, with four triangular divergent teeth, the two in the middle being the largest 

 and farthest advanced. From the middle bifurcation of the clypeus there is a deep groove 

 continued about half its length backwards. The feet are without hairs. The chelae of fore- 

 feet are thick, and serrulated on the inside. The other four pair of feet have thick knees, and 

 subchehform claws. The only specimen brought home by Dr. Smith has lost of the external 

 antennae all but the two first joints. 



Sub-genus. Mithrax, Leach. 



Sp. 5. ( ) Mithrax qnadridentatus, n. s. 



Descr. Mithrax cornubus rostri divergentibus ad apicem arcuatis, extus bidentatis dente apicali 

 multo majore; testi triangulari supra granulosa, baud spinosa, marginibus lateralibus anticis 

 quinqiiidentatis . 



Note. Carapace and feet exactly like those of Mithrax dichotomus, Lat., to which this species 

 comes exceedingly close. The anterior lateral edges of the shell are armed on each side, 

 as in M. dichotomus, with seven spiniform teeth ; but the hinder two of these teeth are evanescent, 

 and are placed more on the back. There are, moreover, no points on the hinder edge of 

 the carapace, as in M. dichotomus. The eyes are globular, and lai'ger than the base of the 

 pedicles. The antennary fossa has no tubercle at the posterior edge. The anterior feet are 

 long, having the third and fourth joints covered with short spines : the fifth joint or hand is 

 slender and smooth, as is also the moveable finger without teeth. The other feet have no 

 tooth at the extremity of the third joint. The size is inch. 



6. By means of Eurynome we proceed to the Parthenopina ; but of this groupe no species 

 has been brought from the Cape ; so we avail ourselves of Cryptopoda to pass on to jEthra, 

 and so among the Cancrina, of which the families appear to be as follow. All these families are 

 distinguished by having the scapes of the palpi of the fifth maxillae unidentated on the outside ; 

 and their males have the genital orifices hollowed out in the first joints of the hind feet. 



