200 



ALLAN HANCOCK PACIFIC EXPEDITIONS 



VOL. 8 



Type locality. — Holotype and 2 paratypes from Station 701-37, 32 

 fms., sand and shell, Angeles Bay, Gulf of California, Mexico, March 20, 

 1937. Four paratypes from Station 650-37, 47 fms., coarse sand, off San 

 Francisco Island, Gulf of California, Mexico, March 9, 1937. One para- 

 type from Station 1249-41, 34-44 fms., fine white sand, one mile south 

 of San Benito Islands, Lower California, Mexico, February 26, 1941. 



Remarks. — The youngest specimen measures R=5.2 mm., r=3.2 

 mm., R=1.6 r, width at base of ray (second superomarginal plate) 2.7 

 mm. It has 7 very large, rectangular superomarginal plates separated 

 from one another by deep fasciolar grooves, and 14 adambulacral plates. 

 The terminal plate is conspicuous, large and convex, raised above the 

 abactinal surface. Anal aperture is barely visible. Paxillae bear a central 

 and 6 or 7 peripheral spinelets. There are 3 or 4 ambulacral furrow 

 spines. Each mouth plate bears 3 large oral spines. Actinal interradial 

 series consists of 7 plates. The madreporite is small, partly concealed by 

 crowded paxillae, and located in the median interradial area. 



Relative Dimensions of 

 Leptychaster (Parastropecten) stellatus 



This species is closely related to Leptychaster (Parastropecten) in- 

 ermis (Ludwig) of the tropical Pacific but differs from it in having 6 

 papulae instead of 4 around each plate; proximally 4, rarely 5, and dis- 

 tally 3 furrow spines instead of 6 or 7 ; a more stellate disk, longer arms, 



