374 A. E. Verrill — Decapod Crustacea of Bermuda. 



longed and is rounded distally. Hence I am disposed to consider 

 the grou}) including P. Sayi a distinct genus. 



In these characters this species agrees with P. pelagicus, the type 

 of the genus. I have compared it with a number of characteristic 

 specimens of the latter from Japan. (Yale Mus., coll. E. S. Morse.) 



Charybdella JI. J. Eathbim, 1897=Cronms Stimpson, 1860 (name preoccupied). 



This genus was established for C. rubra, as the only species. The 

 latter, which is a common West Indian and Florida species, differs 

 from our species of Acheloils in several important characters. Its 

 outer maxillipeds have the merus short ; the manus of the chelipeds 

 bears three distal s}>ines ; the antero-marginal teeth are alternately 

 larger and smaller ; the antennal sinus of the orbit is much con- 

 tracted ; the inner orbital tooth is deeply bilobed. But the 67m- 

 ryhdella tuniidula, referred later to the same genus by Miss Rathbun, 

 would seem to go about as well in Acheloils, where it had previously 

 been placed, for its characters are partly intermediate between the 

 two genera. In most respects it is very closely related to A. Gibbesii, 

 which it closely resembles in the strong areolation of the carapace ; 

 the frontal denticles; and bilobed interorbitals ; the distal denticula- 

 tion of the merus of the swimming feet, etc. But owing mainly to 

 the alternation of large and small marginal teeth, I have left it in 

 Charybdella. The characters of the antennal sinus and antennae 

 are intermediate. 



Some special diagnostic characters of the Bermuda s2Jecies (and some others 

 nearly allied) of Portunus, Acheloils, and Charvbdelta. 



1. — Carapace convex, nearly smooth, glossy, with feeble areolations and few 



hairs - - - Sayi 



2. — Lateral marginal teeth alternately distinctly larger and smaller. 



tumidula ; rubra 



3. — Posterior corners of carapace distinctly angular spinicarpus 



4. — Posterior lateral marginal spine scarcely longer than the rest, .dejjressifrons 

 5. — Inner orbital tooth bilobed, so that the front has eight teeth or lobes 



between the orbits, counting the inner orbitals. 



tumidula; rubra; Smithii ; Gi56esi't (bilobing feeble) ; spinimanus 

 6. — Carapace when fresh having a pair of well defined, round, ocellated, red 



spots on the flanks Sebre 



1. — Carapace having a pair of ill defined red or brownish spots on the flanks. 



tumidula 

 8. — One or two round silvery spots on each side of carapace, near bases of 



marginal spines Gibbesii 



9. — Merus of chelipeds having five or six spines on the inner margin. 



Gibbesii ; rubra (not always); Sebce ; depressifrons ; spinwnanus (sometimes). 



