ASTEROIDEA 



91 



acral grooves narrow ; adambulaeral plates carrying one furrow 

 spine and another on the outer surface, these two forming a 



Fig. 51. — Porania pulvillus, oral side. Slightly reduced. (From Dan- 

 mark's Fauna.) (An excellent figure of the dorsal side of this species 

 is given in Bell's Catalogue Brit. Echinod., PL X.) 



regular double series of spines along each side of the ambulacral 

 grooves. R = ca. 1-5-2 r. Grows to a size of ca. 110 mm. diameter. 

 Colour in life bright red or yellowish- 

 white, spotted or mottled ; the 

 under side white. Altogether a 

 very beautiful sea-star. 



Regarding its food it has been 

 proved that detritus, drawn into 

 the stomach by ciliary currents, 

 pla3^s an important role ; larger 

 animals have not been found in its 

 stomach, and it appears that it will 

 not eat in aquaria. 



The larva (Fig. 52) is a Bipin- 

 naria with a Brachiolaria stage, 

 peculiar through its short arms and 

 through having a series of papillae 

 along the edge of the Brachiolaria 

 arms. 



In British seas this species 

 occurs along the southern, western, 

 and northern coasts, down to the 



Fig, 52. — Larva, in the Bra- 

 chiolaria stage, of Porania 

 pulvillus. Ca. X 25. (After 

 Gemmill ; from Dantnark's 

 Fauna.) 



h, Hydrocoel, or watervascular systoiii ; 

 ]), Papilhp; s, Suckin<? disk. 



