438 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 21 



Habitat: Gray sandy mud. (Garth, 1948) Velero III specimens 

 were dredged 6 of 9 times in sand, with shell present with the sand on 

 two occasions. The remaining three dredge hauls were in mud. The 

 single shore collection was from shale. 



Depth: 9-41 m. (Garth, 1948) Hancock expeditions specimens were 

 dredged in from 3-25 fathoms, with one intertidal collection. 



Size and sex: Males are from 6.0 to 11.3 mm (Askoy specimen), 

 females from 6.2 to 20.4 mm, young from 4.0 mm. 



Breeding: The female holotype was said by Stimpson to be sterile. 

 None of the females taken subsequently have been ovigerous. 



Remarks: Parthenope (Parthenope) hyponca is the sole representa- 

 tive in the eastern tropical Pacific of the typical subgenus, which is 

 represented in the tropical western Atlantic by P. (Parthenope) agona. 

 The species was known to Rathbun by description of Stimpson and 

 figures of A. Milne Edwards only, there being no specimens in the 

 collection of the U. S. National Museum as recently as 1937. The first 

 males to be reported were obtained by the Askoy (Garth, 1948), which 

 also extended the range of the species from Panama south to Cape Santa 

 Elena, Ecuador. Velero III material again establishes its presence in 

 northern Mexico, although at Tenacatita Bay rather than Mazatlan, 

 which was A. Milne Edwards's locality. The species was not encountered 

 by the Velero III in the Gulf of California, nor at any of the offshore 

 islands, such as Clarion or Galapagos, nor has it been taken by the 

 Velero IV, which has made but one brief cruise south of Cape Corri- 

 entes, Mexico. 



Subgenus Platylambrus Stimpson 



Platylambrus Stimpson, 1871b, p. 129. A. Milne Edwards, 1878, p. 146. 



Alcock, 1895, p. 261. Rathbun, 1925, p. 516. 

 Enoplolambrus A. Milne Edwards, 1878, p. 147; type: Lambrus carina- 



tus (emendation of carenatus) Milne Edwards, 1834, by monotypy. 

 Lambrus Miers, 1886, p. 92 (part). 



Type: The Atlantic Lambrus crenulatus Saussure, \858 = Lambrus 

 serratus Milne Edwards, 1834, type of Platylambrus Stimpson by sub- 

 sequent designation of Rathbun (1925). 



Description: Carapace carinated or tuberculated, broader than long, 

 broadly triangular with rounded sides and a broad but acute and pro- 

 jecting rostrum; no postocular constriction. Chelipeds with the mero- 

 podite and palm straight, the former [segment] prismatic, the latter 

 sharply trigonal, the anterior and posterior borders of both [segments] 

 sharply laciniate or serrate, as also the outer edge of the carpus. (Alcock) 



