1887.] NATURAL SCIENCES OF PHILADELPHIA. 109 



position of the coalesced basal disc ; a totally ditTerent thing from 

 what the English authors attempted to prove by their figure. 



We are altogether in accord with Goette and Carpenter in their 

 opinion that the orals are represented in the abactinal system by 

 the basals, but we disagree entirely with the latter writer that the 

 basals are represented orally by the proximals. We regard the 

 proximals as an element similar to the interradials, but, while these 

 fill up vacancies in the calyx, the former fill the open space around 

 the peristome as it widens in the growing animal by the increasing 

 width of the dorsal cup. To this conclusion we were led principally 

 by the arrangement of the plates, the presence of radial and anal 

 plates in the same ring with them, and by their gradual appearance in 

 geological times. We further believe the central piece is the only plate 

 which in the Palaeocrinoidea and Blastoidea can possibly represent 

 the quinque-partite oral pyramid. We regard it as being primi- 

 tively composed of five pieces, such as remained intact persistently 

 in Stephanocrinus and most of the Cystidea, but which were fused 

 together by anchylosis in other groups as aborally in the case of 

 the basals, which gradually were reduced from five to three, and in 

 certain groups to one solid piece. The proximals, therefore, in our 

 opinion, are not of that morphological importance as they are regarded 

 by Dr. Carpenter, and we think the same may be said of the so-called 

 radial dome plate*-'. These also, like the proximals, seem to us mere 

 auxiliary pieces, filling u]) vacancies, beneath which the branching 

 of the ambulacra takes place. If they deserve the term radials at 

 all, they certainly represent the axillaries, and not the oculars or 

 first radials, except perhaps in some very complex species in which 

 there appear three successive pieces to each ray, the inner ones rest- 

 ing against the central plate in a similar manner as the true radials 

 rest against the basals ; while the third or axillai^ one holds to- 

 ward the proximals and the ambulacra the very same relations as 

 the single radial does in the simpler form (See Revision Pt. Ill, PI. 

 IV, Fig. 4, and PL VIII, Figs. 1, 3.). It is also very significant 

 that frequently in those complex forms there appear toward the cen- 

 ter tvithin the ring of proximals (orals of Ether, and Carp.), two ex- 

 tra axillaries underneath which the tw^o lateral rays, which are 

 united close to the peristome, divide so as to form the antero-and 

 postero- lateral rays. How Dr. Carpenter will explain the presence 

 -of these plates within the "oral" ring, which is said to cover the ori- 

 gin of the ambulacra, is a mystery to us, and we look to him for in- 



