1895.] NATURAL SCIENCES OF PHILADELPHIA. 183 



6.,. Carapace with two lateral spines and a third very small one be- 

 hind the supraorbital fissure. Rostrum with two minute lateral 

 teeth on each side. Abdomen smooth. Eyes colorless . P. abyssi. 



P. occidental is. 

 b 3 . Carapace with two indistinct lateral keels, each with a spine. 

 Sixth and seventh segments of abdomen feebly furrowed. Ros- 

 trum acute, with a lateral tooth on each side . P. challengeri (2). 

 6 4 . Carapace with one lateral spine and a series of small spinules. 

 Fifth segment of abdomen sculptured, sixth and seventh fur- 

 rowed. Rostrum obtuse . P. pattersoni. 



Og. Median keel of carapace with two spines. 

 b x . Abdomen strongly longitudinal^ and transversely sculptured. 

 Carapace with a two-spined median keel, and two many-spined 

 lateral ones on each side. Rostrum emarginate . . . P. sculptus. 

 b. 2 . Abdomen smooth or only with a few longitudinal keels. 

 Gy. Carapace with distinct and denticulate lateral keels. 

 cl x . Three lateral keels, the upper with two, the lower with one, 

 the middle without teeth. Rostrum truncate . P. bidentatus, 

 d 2 . Two lateral keels, the upper with five, the lower with three 



teeth P. australis. 



c 2 . Carapace with two lateral spines. Rostrum acute, slender. 

 Abdomen without keels. 



d x . Rostrum without lateral teeth P. junceus. 



d 2 . Rostrum with one lateral tooth on each side. Spines of the 



lateral faces of carapace in an oblique plane , . . P. gracilis. 



d 3 . Rostrum with two lateral teeth on each side. Spines of the 



lateral faces of carapace in the same level . . . P. profundus. 



c 3 . Carapace without lateral spines and without distinct keels. 



Rostrum short, obtuse, fifth and sixth segments of abdomen 



with two longitudinal keels P. bispinosus (1). 



a 4 . Median keel of carapace with one spine. Abdomen smooth. 

 b x . Carapace with three lateral spines and a longitudinal series of 



small spinules P. intermedins: 



b 2 . Carapace with one spine on each side .... P. trispinosus (1). 

 6 3 . Carapace without lateral spines. 

 Cj. Rostrum broadly truncate. Telson furrowed . P.fasciatus (5). 

 c 2 . Rostrum short, obtuse. Telson rounded dorsally. 



P. neglectus. 



a 5 . Median line of carapace without spines. Carapace with seven 

 keels, keels smooth, the upper and lower lateral keel with a spine 

 each. Abdomen sculptured by transverse furrows. .P. carinicauda. 

 1. Pontophilus cataphractus (piivi) 1792. 10 



Cancer cataphractns Olivi, Zool. Adriat., 1792, p. 50, pi. 3, fig. 1.. 



10 Eecently there has been described a species by Henderson (Trans. Linn. 

 Soc. London, Zool. (2) V, part 10, 1893, p. 446, pi. 40, fig. 16, 17) from the Bur- 

 mese coast named Aegeon orient 'alis, which is said to be nearly related to the 

 Mediterranean P. cataphractus. 



