258 BULLETIN 97, UNITED STATES NATIONAL MUSEUM. 



PLANES MARINUS Rathbnn. 



Plate 64. 



Plyncs marlnus RATHBUN, Proc. U. S. Nat. Mus., vol. 47, 1014, p. 120, pi. 3 

 (type-locality, at sea, west of Lower California, in lat. 23 49' N. ; 

 long. 127 50' W.; holotype, Cat. No. 6065, 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 tooth 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. 



Habitat. Pelagic. 



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

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

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



