MUSEUM OF COMPARATIVE ZOOLOGY. 119 



Herbst. He refers to Seba, pi xxii, fig. 6. Seba's fig. 22 of pi. xix is a 

 better representation of tbe species under consideration. 



Littoral on the reef at Eastern Dry Rocks. 

 Reef at Cruz del Padre, Cuba. 

 Key West, in 2 to 5 fathoms. 



Family TYCHIDAE. 

 Subfamily TYCHINAE. 



Tyehe emarginata White. 



Tyche emarginata White, Annals and Magazine of Natural Histoiy, First 



Series, Vol. XX, p. 206. # 

 Platyrinchus trituberculatus Desbonne et Schramm, Crust, de la Guadeloupe 



p. 3 ; pi. iii, figs. 7 and 8. 



The curious genus Tyche is so little known that a short description of 

 the crab under consideration may not be out of place here. The carapax 

 is flattened and partly concave above, and has laminiform expansions in 

 front and behind. The frontal region is vei-y broad, the transorbital width 

 nearly equalling that across the branchial regions. The hepatic region is 

 concave. Rostrum rather long, forked from the base ; horns widely diver- 

 gent. Prasorbital spines very long, and somewhat divergent, thus, with 

 the rostrum, giving the entire front a four-horned form. External antennas 

 concealed beneath the rostrum. Eyes long, but reaching scarcely beyond 

 the edge of the expanded orbital margin, which is entire, without notch or 

 tooth. 



The external maxillipeds are very remarkable in form, the exognath 

 having a hook-shaped process at the base, which overlaps the base of the 

 ischium-joint of the endognath. The meros-joint of the endognath has a 

 posterior lobe which projects far into the anterior extremity of the ischium. 



This crab was found by the expedition at Key West in 2 to 5 fathoms, 

 and at the Tortugas in 7 fathoms. 



Family EURYPODIIDAE. 



Among the general characters of this family, the existence of a distinct 

 orbital arch over the base of the eye, and of a postocular spine, seem to be 

 the most important. 



Subfamily COLLODINAE. 



This name is proposed for a group of genera of Eurypodiidae character- 

 ized by the extreme shortness of the rostrum, which group is, as far as 

 known, peculiar to the tropical parts of the American seas, and occurs on 

 both sides of the continent. 



