Il8 NEW YORK STATE MUSEUM 



in the corners of the disk, no other species of this genus or any- 

 other Devonian auluroid seemed to exhibit a like strong development 

 of the accessory marginal plates. The rays are slender, hardly if at 

 all petaloid in form, but regularly tapering; they probably extended 

 no more than half their length beyond the disk. The specimen 

 shows only the abactinal or dorsal view of the ambulacrals, which 

 are distinctly alternate, subquadrate, half vertebra-shaped with 

 raised distal and proximal margins. Proximally the two columns 

 end in the strong, simple, curved jaws which carry the rather 

 long and slender syngnaths. 



The adambulacrals are, as in some other Encrinasters, not seen 

 on the dorsal side within the disk; outside of the latter they could 

 be observed only in one place as thin, obliquely rhomboidal plates 

 that lie opposite the ambulacrals. 



Compared with its congeners, this form in its aspect differs from 

 most others by the large disk and narrow, hardly petaloid rays. 

 In the latter feature it compares well with E . a r n o 1 d i Gold- 

 fuss, but it differs from all in the double and threefold columns of 

 marginal disk plates. Its mouth frame is exactly as in the other 

 Encrinasters. With E . pontis Clarke, another South Ameri- 

 can (Devonian) species, from Ponta Grossa, Parana, Brazil, it 

 possesses considerable similarity in the form of the rays and in 

 the shape of the ambulacrals which are exactly alike in the abactinal 

 view, as well as in that of the jaws ; but it would seem that E . 

 pontis, while altogether a smaller species, had also a relatively 

 much smaller disk (the latter only seen in one specimen) and 

 lacked the strong, or any, development of the marginal plates. 



Argentinaster bodenbenderi nov. 



Plate 18, figures 6 and 7 



The species described in this chapter can not be brought under 

 any known genus of starfish. It is distinctly an Auluroid but has 

 certain characters of the genera Encrinaster, Hallaster and Squa- 

 master without fully agreeing with any of them. 



The disk is distinct, with concave margins, and three large 

 distinct marginal plates which belong to the adambulacral column, 

 only the ambulacrals continuing to the mouth. The rays are 

 slender, regularly tapering; on the actinal side they show opposite 

 highly projecting, pipe-bowl-shaped crests, turning the bowls 

 toward each other and in the deep interspaces a distal buttonlike 

 prominence, with the podial pores on either side. The ambulacrals 



