\ \\ I II. .(Ill 1 1 - 



middle, tin- plat'- .f iiisrriii.ii .if medium -i/. 

 ish. Itl'tiiii'., Diet. Sc. Nat. xxxvi. p. 5i 



/' yrv/e. 



\ i;i:i: IJlainv. IJody oval, elongated, :i littlr vermiform 

 having the irirdle vrry thick and very wide, covered with ijiiitr tine 

 hair- and small lulls. Shell small, occupying only a third ot 

 hack, formed of S thin, fragile valves, the intrnnrdiate ones larger 

 than the terminal, exposed portion triangular and very small in 

 comparison with the plates of insertion, which are win;: shaped. 

 Insertion-plate of the anterior valve especially large, 6-lohed ; that 

 of the posterior valve patelliform, with 4 lobes. General color of 

 the shell whitish -ray. (/>/>iinr., Diet. Sc. Nat. xxxvi, p. .>j3.) 



Seas of New HoWm<L 



Section Sotoplax H. Adams. 



Xntnpt,,.,' A i)., P. 7. S. 1861, p. 385 (type N. speciosa H. Ad.). 

 M,n>an'lre!ln CPK. MS. in DALL, Proc. U.S.Nat. Mus. 1381, pp. 

 284, 288 (type M. plumeusCpr.') 



Acanthochites in which the posterior valve has the insertion -pi" t<- 

 yrnnreil outride and denticulate at the edge, between the usual two 

 latero-posterior slits. Tegmentum reduced in size by the encroach- 

 ment of the girdle at the sutures, the valves nearly or whollv 

 separated there. Anterior valve not distinctly ribbed radially, or 

 lobed around the edge. 



A rather weakly characterized section, probably artificial, but 

 decidedly convenient at present as a means of splitting the i; 

 mass of Acanthochites. It is intermediate between typical Acnuth"- 

 i-liitfn and Oryptoconchus in characters. The girdle has the tufts 

 rather smaller than in the more typical Acanthochites, and the 

 spicular covering of the whole surface varies from nearly obsolt 

 a druse clothing. 



The true nature of the girdle in Notopla.r was not known {<> I>r. 

 l)all when he wrote the notes upon the group in Bull. Mus. Comp. 

 /'"I. xviii, p. 417. In the typical species, N. speciosa, it exhibit? 

 all the characters of the girdle of Acanthochites. There seems to be 

 no character of more than specific value separating Xfi>/,i.r and 

 M-i^nnhflliis. As to Stectopla.r, which Dall (/. c.) thinks may prove 

 to equal Nntnpl.i.,-, it is absolutely nothing but a <remiine .' 

 chites. 



