ASTEROIDEA 75 



12^^ 41' W., 1767 m. ('" Helga "), and further at 50° 22' N., 

 11° 44' W., 1797 m., and 57° 41 ' N., 11° 18' W., 1853 m. (" Michael 

 Sars "). It has otherwise only been found by the '' Challenger " 

 off the coast of Portugal (depth not recorded). 



Possibly this species is identical with Benthoj^ecten sjnnosus 

 Verrill from off the N. American coast (ca. 42° N. to the Mexican 

 Gulf), which may again be identical with Pararchaster simplex 

 Perrier from the West Indies. The latter name, which is the 



Fig. 41. — Benthopecten armatus. Dorsal side. Nat. size. (After Grieg, 

 EcMnod. " Michael Sars'', 1921.) 



oldest, should then be adopted. But the identity of the European 

 and American form can hardly be said to be beyond doubt, and 

 it is therefore the safest course, for the present, to use the name 

 armatus for the European form, the name spinosus for the 

 American form. 



3. Suborder. Valvata Perrier. 



Dorsal side with paxillae, spines or naked. Marginal plates 

 mostly very conspicuous, covered with grains or spines, not alter- 

 nating. Pedicellariae, when present, mostly valvate, more rarely 

 simple. One or two large, recurved, hyaline spines may occur 

 on the jaws. Tube-feet with a sucking disk. No paired dorsal 

 arm muscles. 



