ASTEROIDEA 



627 



L. foliolata Grube. Similar to above, but with heavier and more 

 spines on oral surface; size 30 to 50 cm.: Pacific coast from Alaska to 

 Mexico, below low-water mark to 190 fathoms; often common. 



L. senegalensis (Lamarck). Similar to the above, but with 9 arms; 

 size 30 to 35 cm.: Florida and the West Indies; west coast of Africa. 



Family 2. 

 PORCELLANASTEEIDAE. 



More or less pentagonal 

 starfishes with a membranous 

 aboral wall covered with paxil- 

 lae, in the middle of which rises 

 a tube-like epiproctal projec- 

 tion; anus wanting"; 2 rows of 

 thin porcelain-like marginal 

 plates without spines; between 

 certain of these plates occur 

 vertical rows of thin folds of 

 the integument called cribri- 

 form organs: 25 species. Fig. 972 — Ctenodiscus crispatus (Fisher). 



Ctenodiscus Miiller and Troschel. Body stellate or pentagonal; 

 paxillae on the aboral body wall: 1 species. 



C. crispatus (Retzius) (Fig. 972). Size 7 to 10 cm.; form of body 

 very variable, from pentagonal to stellate: circumpolar, ranging south- 

 wards to California and Cape Cod, from shallow water to 1,000 fathoms; 

 often common off New England; Panama. 



Family 3. GONIASTEEIDAE. 



Flattened, usually pentagonal starfishes 

 with 2 rows of veiy large marginal plates; 

 plates in the aboral wall forming a mosaic, 

 sometimes with paxillae: 40 genera. 



1. Mediaster Stimpson. Upper marginal 

 plates separated by paxillae; aboral plates with 

 paxillae : 6 or more species. 



M. aequalis Stimp. Papulae in twos and 



threes; color in life, bright red; size 10 to 15 cm. : 



Alaska to Lower California, in 9 to 1G7 fathoms. 



2. HlPPASTERIA Gray. Principal skeletal plates each with a central 



tubercle ; marginal plates with tubercular spines : 5 species. 



H. pharygiana (Parelius) (Fig. 973). Size 15 to 20 cm.; upper 

 surface bright red in life: north of Cape Cod, in 20 fathoms or more. 



Fig. 97.3 



Hippasteria pharygiana 



(Verrill). 



