ASTEROIDEA OF NORTH PACIFIC AND ADJACENT WATERS — FISHER 



117 



Specimens examined. — Forty-two, of which 15 are in the young fissiparous, 

 6-rayed stage. 



Specimens of Sclerasterias heieropaes examined 



' Probably error in station number. 



Remarks. — Geographically the species nearest to heteropaes are S. euplecta 

 (Fisher), Hawaiian Islands, and S. alexandri (Ludwig), Gulf of Panama. Stolasterias 

 robusta Ludwig from 704 meters, south of Chatham Island, Galapagos, is a Distolas- 

 terias, in the restricted sense. I have examined specimens of all three species. Alex- 

 andri has a rather more delicate skeleton than heteropaes, with all the spines (including 

 inferomarginal) slenderer, terete, regularly tapered and sharp. The inner, or lower, 

 inferomarginal is conspicuously shorter and slenderer than the outer and may be 

 faintly compressed. The dorsolateral spines are lacking. The wreaths of pedicel- 

 lariae are less voluminous, the integument thinner, and the crossed pedicellariae both 

 in the adult and fissiparous young stages differ in detail. (PI. 52, figs. 2 and 3.) 

 The carinal and marginal plates do not overlap so strongly as in heteropaes so that the 

 spines are more distantly spaced. There is an incomplete series of small actinal 

 plates but no spines. The adambulacral spines are a little more delicate, and on the 

 first two or three plates, as well as here and there along tho ray there may be only one 

 spine. On the outer third of the ray the plates may alternate with one and two spines ; 

 and finally near the tip there is usually only one spine. The mouth angle is a 

 little broader than in heteropaes, with one pair of contiguous adambulacral plates 

 (R = 45 mm.). The mouth spines are slender, tapered, blunt, and not gouge-shaped. 



A very important feature of dexandri is the presence of a delicate web, connect- 

 ing (with deep emarginations between) the outer inferomarginal spines. This web 

 meets the spine about two-thirds the distance from base to summit and bears on the 



