268 Records of the Indian Museum. [Vol! XXIV, 



We know nothing of the oral appendages in this genus. Cou- 

 tiere states that the apex of the telson is armed with only two 

 short spines placed close together and it is thus possible that the 

 genus does not belong to the subfamily Pontoniinae. 



Genus Stegopontonia Nobili. 



1907. Stegopontonia, Nobili, Mem. Accad. Sci. Torino (2) LV1I, 

 p. 360. 



This genus was proposed for S. commensalis, Nobili, of which 

 a single specimen, found on the Echinoid, Echinothrix turcarum, 

 was obtained in Hao I,agoon, Paumotu Group, Polynesia. Stego- 

 pontonia differs conspicuously from the related genera in the posses- 

 sion of a double basal protuberance on the dactyli of the last three 

 pairs of legs. The rostrum is depressed, toothless, concave above, 

 and wider near the middle than at the base ; the only spine on the 

 carapace is the antennal Nobili gives no description of any of 

 the mouth-parts or of the telson. 



Genus Coralliocaris (Stimpson). 



1852. Oedipus, Dana, U. S. Explor. Exped., Crust. 1, p. 572. 

 i860. Coralliocaris, Stimpson, Proc. Acad. Sci. Philadelphia, p. 38. 

 1917- Coralliocaris (excluding subgen. Onycocaris), Borradaile, Trans. 

 Linn. Soc. (2) Zool. XVII, p. 381. 



Borradaile follows Nobili in recognising two subgenera of this 

 genus, Coralliocaris and Onycocaris , but the proper position of the 

 two species for which the latter name was proposed [see p. 278) 

 appears to me to be very uncertain. I do not think there is any 

 justification for including them in Stimpson's genus. 



Thus restricted the genus Coralliocaris forms a compact group 

 of species, all of which so far as is known live in association with 

 madrepore corals. In general facies they agree very closely with 

 HarpiliiiSy which has adopted the same habitat, but they are at 

 once distinguished by the presence of a very large basal protuber- 

 ance on the dactylus of the last three pairs of legs. 



Coralliocaris is distinguished from Conchodytes b)' a number 

 of well-marked characters. The rostrum is compressed, dorsally 

 carinate and commonly bears teeth. The antennal spine of the 

 carapace is always present, the hepatic present or absent. The 

 inner lobe of the maxillula is slender and the distal endite of the 

 maxilla is narrow and furnished with setae only at the tip. The 

 dactylus of the last three pairs of legs is provided with a single claw 

 and the basal protuberance, in all the species I have examined, is 

 swollen and hoof-shaped. 



Borradaile in his synoptic key separates the species of this 

 genus mainly by the number of rostral teeth. In this character, 

 however, there is much variation. Other and better characters 

 will no doubt be found, but at present the descriptions of several 

 species are very imperfect. Miss Rathbun's C. atlantica 'from the 



1 Rathbun, Hull. U. S. Fish Comm. XX, p. 122, fig. 26 (1902). 



