1886.] NATURAL SCIENCES OF PHILADELPHIA, 209 



of two adjacent radials, and an inner portion or deltoid/ and 

 that the calyx consists of three rows of plates the basals, radials 

 and deltoids. The canals which contain the food grooves are in 

 their usual preservation, more or less compressed, and in conse- 

 quence thereof the two series of covering pieces became separated 

 longitudinally, and appear in the specimens as if forming a deep 

 groove upon the surface following the median line. Little of this 

 groove, however, is seen in plump specimens. 



Etheridge and Carpenter, and also Zittel, regard the two rows 

 of anchylosed covering plates as constituting a single piece, and 

 this, they think, represents the lancet plate of the Blastoids. 

 Upon this point they make on p. 240 of their paper the following 

 statement : " The paired linear plates in the ambulacra we believe 

 to be single, and to represent the lancet plates of other Blastoids. 

 They seem to be usually much eroded and to have a strongly 

 marked median groove, which has been taken for a suture. Even 

 when these plates are preserved the side plates of the ambulacra 

 are generallj'^ missing ; but since Hall has discovered specimens 

 of S. angulatus still attaining ambulacral appendages like those 

 of other Blastoids, we see no reason to doubt the existence of 

 side plates and outer side plates. In fact, the former have been 

 described in S. pulchellus by Miller and Dyer." We doubt if 

 Etheridge and Carpenter ever saw a Stephanocrinus with either 

 side pieces or outer side pieces, or ever will see one, and if Miller 

 and Dyer found such plates in their St. pulchellus, we assert that 

 their species is not a Stephanocrinus. Aside from the fact that 

 the " so-called lancet pieces " are compound structures, we think 

 it utterly impossible from the position which these plates occupy 

 toward the oral plates, that the^'^ could represent lancet pieces, as 

 in that case the food grooves would have to run out into the air 

 in place of entering the interior. 



In both of the New York species, the oral plates are on the 

 same level with the covering pieces ; they meet with each other so 

 as to leave externally, when both plates are in position, no open- 

 ing or passage. The only communication with the inner cavity, 



^ We have substituted here deltoids for ^^oraJs,^' the latter term being 

 used by Etheridge and Carpenter in their paper. When they wrote this 

 they still regarded the deltoids as representing the orals, a mistake which 

 Dr. P. H. Carpenter explained and corrected in his Challenger Report, 

 p. 162. 



AC 



