CANCROIDEA. 293 



121). It was placed near Gecarcinus by Dr. Randall; but the inser- 

 tion of the male verges is in the bases of the posterior legs and not in 

 the sternum. It has the fourth joint of the outer maxillipeds articu- 

 lated with the outer apex of the third, as in Trichodactylus. But the 

 general form of the body is much more convex, and the third joint of 

 these maxillipeds is narrow oblong, and but slightly shorter than the 

 second. The antero-lateral margin of the carapax is denticulate. 

 The texture of the shell resembles that of the other Telphusidse. 

 The male abdomen is quite broad triangular. The palate is not 

 divided by two longitudinal ridges as in the other Telphusinea, and it 

 is probable that the Orthostomata should constitute a distinct family. 

 These ridges are, however, rather indistinct in some TelpbusaB. The 

 Orthostomata appear to form a transition between the Telphusidse and 

 the Gecarcinidse ; there is a resemblance to the latter in general form, 

 as well as in the absence of these ridges. 



The genus Galene arranged with the Eriphidse, has close relations 

 to this group. 



Many Crustacea of this family were collected ; but, the unfortunate 

 loss of the Peacock was the loss of all the specimens, excepting a Tri- 

 chodactylus. 



From the occurrence of the species of Telphusinea mostly in fresh 

 waters, they are properly called the Cancroidea Fluviatica, while the 

 other species already described are the Cancroidea Marina. The 

 peculiarity in the branchial cavity is connected with this peculiarity 

 in their habits. 



G-. I. Telphusa, Latr. — Articulus maxillipedis externi 3tius subquadratus, 2do 

 nmlto brevior, 4turu angulo apicali interno gerens. 



Gr. 2. Valdivia, White. — Articulus maxillipedis externi 3tius oblongus, 2dus 

 transversus. [Carapax margine antero-laterali 4-dentatus.] Pedes longi. 



Gr. 3. Potamia, Latr. — Articulus maxillipedis externi 3tius subquadratus, apice 

 subtriangulatus anguloque apicali 4tum gerens. 



Gr. 4. Trichodactylus, Latr. — Carapax marginibus subinteger. Articulus 

 maxillipedis externi 2dus oblongus, 3tius vix oblongus, subtriangulatus, margine 

 terminali valde obliquo anguloque externo 4tum gerens, 2do multo brevior. 



Gr. 5. Orthostoma, Randall. — Carapax margine antero-laterali dentatus. Arti- 

 culus maxillipedis externi 2dus oblongus, 3tius oblongus, 2do paulo brevior, 

 apice obliquus, prope angulum exteriorem articulum 4tum gerens. 



74 



