Verrill, Kotes on Radiata. 569 



There is but one specimen of this species in the collection, which 

 has been dried from alcohol. It is more nearly allied to P. pulvlllus 

 Sars* than to P. militaris. The latter has much longer arms and only 

 three or four spinules on the dorsal paxillae; the formtr has more 

 numcrons spinules on the paxilla?, shorter and more numerous inter- 

 ambulacral spines, and quite different mouth-spines. The dorsal sur. 

 face is also different from that of either species, as well as the propor- 

 tions. 



Plagionotus Africaiius Veniii, sp. nov. 



Test broad oblong-oval, somewhat angulated opposite the interam- 

 bulacra, truncate and slightly emarginate anteriorly, obliquely trun- 

 cate behind ; margin rather high and abruptly rounded, especially at the 

 anterior end ; upper surface slightly convex, in one specimen depressed 

 at the center. Ovarial openings four, large, the two anterior oblong 

 and divergent, unequal, the others round. Anterior ambulacrum 

 broad, slightly depressed, the plates large and nearly as high as broad, 

 perforated by conspicuous double pores. Anterior lateral ambulacra 

 very divergent, rather broad, narrow at first, increasing rapidly in 

 width to the middle or beyond, the outer portion broad, oblong, 

 obtuse at the end, which is slightly recurved. Posterior ambulacra 

 considerably longer, little curved, but strongly divergent, usually 

 increasing in width to the outer third, beyond which they are some- 

 what narrowed and curved forward. The anterior and posterior inter- 

 ambulacra are, therefore, relatively broader than in P. pectoralis^ and 

 the lateral ones narrower. Peripetalous fasciole narrow, but well 

 defined and sunken, with a rather regular oval outline, which is only 

 slightly angulate, or rather undulated, laterally, but beyond the mid- 

 dle of each anterior interambulacrum it bends downward nearly at 

 right angles for a short distance, and then, after forming another simi- 

 lar angle, bends a little downward in crossing the anterior end. A 

 slight ridge, corresponding to the angle of the fasciole, extends upward 

 to the center, dividing the interambulacra into two unequal areas, the 

 smaller of which is next to the anterior ambulacrum; both of these 

 areas bear oblique rows of large tubercles, which do not extend over 

 the dividing ridge. 



In the lateral interambulacra the very large tubercles are numer- 

 ous, extending to near the apex, mostly arranged in oblique, more or 

 less curved rows ; in the posterior area they are more unequal in size 



* Oversigt af Norges Echinodermer, p. 62, Tab. 6, figs. 14-18, Tab. 7, 8, Christiania, 

 1861. 



