528 PROCEEDlNdS OF THE NATIONAL MVfiKUM. 



tailing into each other so that the lingers do not, gape (tig. IS, h). 

 Ambulatory legs not very long; incri lliit, widening slightly toward 

 the middle; v/,\,\'\n ratlmr wide; i)ioi)o(li short and l)roa<l; dactyli about 

 as long as posterior niaigin of propodi. 



JHmcnsions. — Male: Length, 23.5 mm.; width, M.'S mm.; width of 

 front above, J0.7 mm.; below, 0.8 mm.; greatest dei)th, about 1.<J mm. 



Types. — No. 74-5;3, lirit. Mus. ; two males; Moyomband)a, l*eru; Purdi 

 Higgins. 



POTAMOCARCINUS M iliie-Eclwards. 



J'olamocarciinis Milnk-Edwakds, Ann. Sii. Nat., 3d S(M-., Zool., 1853, XX, ]>. 208 

 1 174] ; An^h. iMiis. lliHt. Nut. Paris, 1851, Vli, ji. 171. TyP", ''• armaliis Milue- 

 KdwaidH.— Ratiiiuin, Vim-. II. 8. Nut. Mus., 18!)3, XVI, }». G55.— Outmann, 

 Zool. .lithib., Syst., 1897, X. pp. 2!»8, 315 (part). 



Kivf/nlrya Outmann, Zool. .lahrb., Syst., 1897, X, pp. 298, 324. Typo, Totamia 

 latifroHH Uaudall. 



I have set apart under the Uiime I*<>t(tm<>rarc,ini(s those si)ecieH which 

 have the 8Ui)eiior frontal margin ovc^rhanging the front, which is rap- 

 idly retreating; thc! orbits very deej), the margins above and below 

 making deep, semi(;ircular incisions in the carapace, and having below 

 two angular sinuses, and the antero-lateral teeth largo and spiniform. 



To this genus I leler P. armatas Milne Tidwards (type species), /*. 

 nicaraguriisis Uathbun, and /'. latij'roiis [\iiuuhil])=Pota)nia schom- 

 burgkii White, 1847,' nomen nudum (type examined).*^ 



T have not adopted the genus Khif/shu/a Ortmann for the following 

 reasons: The genus is established on two characters, namely, the union 

 of the inner orbital angle with the front, and the reduction of the 

 exoguath of the third maxilliped. An examination of the species of 

 I'seudotliclphnsa having a very short exognath (p. 51.'}) will convince one 

 that this is but a si)eci(ic character. As to the nnion of the front and 

 the orbital angle, this chai'acter is open to the objection stat(Hl under 

 lljIlioUtbocera (p. 5()1)). Kven in the type specimen of Pntamia htiifronH 

 Kandall {Khif/.slcj/a Ortmann), the two sides are not symmetrical. On 

 the right side the front unites with the orbital margin, but on the lettit 

 does not, there being between them a hiatus in which lies the tlagellum. 

 The iniM^r suborbital lobe is i)resentji)n both sides, but is almost (entirely 

 hidden. KintjsU'iid is therefore considered a synonym of I'otantocarcinus. 



ANALYTICAL K K Y TO TIIR SI'UCJIICS Ol' I'OTAMOrAKCINUS. 



A. Exoguath reduced to a stump, less Mian ouo-tliird t\w length of the ischium 

 of th(< (indogiiath lalifioiia 



A'. Exognath mor»< than one-third tho length of the iscliium. 



]?. (Jarapa(H) more thau 1 A tinuis as wide as long (ineluding H]»iuos) . ni<ara(/ueiixin 

 JV. Carapace less than l\ times as wide as long (including spines) annaliia 



' List Spec. Crust. Coll. Brit. Mus., p. 30. 



• PotamoiarcinuH dinlicahitiiH Slimpson, I'roc. Acad. Nat. .Sci. I'hila., 1801, XIII, p. 

 373, from the Riv<^r Atrato, United Slatt^s of Colombia, is indeterminable from tho 

 brief des(!ription. The tyjie is not oxtaiit, and Hpecimeus have not since bl^en col- 

 hntod from the same locality. It is jirobably a rucudolhelphiina, and if so, the uamu 

 Pa. denticulata is preoccupied for another species (lescrib(^d by Milne-Edwards. 



