258 BULLETIN 97, UNITED STATES NATIONAL MUSEUM. 



PLANES MARINUS Rathbun. 



Plate G4. 



Planes marinns Rathbun, Proc. U. S. Nat. Mus., voL 47, 1914, p. 120, pi. 3 

 (type- locality, at sea, west of Lower California, in lat. 23° 40' N. ; 

 long. 127° 50' W,; holotype. Cat. No. G0G5, M. C. Z.). 



Diagnosis. — Carapace depressed about the middle; postero-lateral 

 margins nearly straight. 



Description. — Carapace convex antero-posteriorly and from side 

 to side; surface covered with punctae and fine reticulations; coarser 

 striae cross the anterior half transversely and nearly all the 

 branchial region obliquely. Surface of front covered with short 

 striae and minute granulation; free edge arcuate and faintly bilobed, 

 each lobe appearing in front view slightly bilobed; edge a raised 

 finely granulated rim; post-frontal lobes low. Antero-lateral mar- 

 gins convex, with one blunt tocth behind the tooth at the angle of 

 the orbit; postero-lateral margins nearly straight, convergent. 



Chelipeds equal, massive ; upper and lower margins of arm trans- 

 versely striated, inner expansion irregularly denticulated ; outer sur- 

 face of wrist finely striated, tooth at inner angle blunt; surface of 

 palms nearly smooth, shining, punctate, upper surface rounded, cov- 

 ered with finely granulated longitudinal lines which become oblique 

 proximally. Fingers stout, prehensile edges narrowly gaping, den- 

 tate, a larger tooth at middle of fixed finger. 



Legs short and broad; third foot one and one-half times as long as 

 carapace; merus of third pair three-fifths as broad as long; dactyli 

 short and stumpy, armed with coarse spines. 



Many species of Planes have been described in the past, all of 

 which are referable to variations of P. minutus; but this form 

 appears to be distinct. It has a great resemblance to Pachygrapsus 

 also, and forms a link between the two genera. 



From Planes minutus it differs in its broader carapace, somewhat 

 depressed about the middle instead of uniformly convex; in the 

 postero-lateral margins being nearly straight, as in Pachygrapsus.^ 

 not arcuate as in Planes minutus; in the more extensive striation of 

 the dorsal surface; in the broader basal joint of the antenna; the 

 broader merus-joint of the outer maxilliped, both its inner and 

 outer lobes being more strongly developed ; in the feebler dentation 

 of the distal end of the inner expansion of the arm. 



Measurements. — Holotype male, length of carapace 17.6, width of 

 same 19.3, width of front 10 mm. 



Ilahitnt. — Pelagic. 



Material examined. — "West of Lower California, Mexico; lat. 23° 

 49' K; long. 127° 50' W.; surface; D. D.Raulet, collector; male holo- 

 type (GOCr), M. C. Z.) ; 1 male, 1 female, paratypes (22833, U.S.N.M.). 



