25 



cuneiform plates that belong to the arms. There are, therefore, 

 seventeen arms in this species, four in each of two radial series 

 and three in each of the other three series. The arms appear to 

 be composed of a single series of cuneiform plates. 



The first interradials are the larger plates of the body and have 

 nine sides. The second regular interradials are about half as 

 large as the first and they are each followed by three plates, a 

 small one on each side at the base cf the arms and a large one 

 that unites with two large plates in the interradial depression ou 

 the vault. There are no intersecondary radials. There is, how- 

 ever, a distinct azygous area shown in our specimen on the side 

 nearest the proboscis. The first and second interradials are like 

 those in the other areas, but the second plate is followed by four 

 or five plates (the sutures are not all distinct), that separate the 

 arms, one-fourth more than they are separated in the other areas, 

 and these unite with three or more plates of the vault, instead of 

 with two as in the other area.s-. 



The vault is moderately convex and depressed in the interradial 

 areas. It bears a long subcentral proboscis ou the azygous side. 

 It is covered with large polygonal plates that are densely covered 

 with tubercles. The two interradial plates, in each regular area, 

 that abut upon the last interradial in the calyx, are elongated and 

 the larger plates of the vault. There are no pores or passages 

 that penetrate the vault between the arms. 



This species most resembles D. venuftlu^, from which it is dis- 

 tinguished by having seventeen instead of eighteen ai'ms, and by 

 having an azygous area. The surface ornamentation, too, is differ- 

 ent, but on that ground alone we would not be justified in found- 

 ing a new species in this genus, for we are satisfied the sculptur- 

 ing is not uniform on specimens belonging to the same species. 



Found in the Hamilton Group, at Charleston, Indiana, and now 

 in the collection of Wm. F. E. Gurley. 



DOLATOCKINUS APPBOXIMATUS, n. sp. 



Plate III, Fir/. 4, based view: Fitj. 5, summit rieir; Fig. 6, side 

 view, shotving the three armed radial series. 



Calyx bowl-shaped; truncated below; slightly constricted below 

 the arm bases; pentagonal, funnel shaped columnar pit, bounded 

 externally by a raised ridge running from a central tubercle on 

 —4 G. 



