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\ f iW | 646 THE CRINOIDEA CAMERATA OF NORTH AMERICA. f 
I di | which the two genera can be separated in the fossil state. Hucladocrinus is 
1 | { " an extravagantly developed Platycrinus, and should perhaps be regarded as 
I \| | a subgenus. — 
nt. | i Coccocrinus was placed by Miiller and Roemer among the Platycrinide ; | 
i) } i by Pictet, Dujardin and Hupé, Zittel, and §. A. Miller, under the Haplo- zi 
| | ; i crinide ; while at the same time the latter authors refer the closely allied 
y / | Culicocrinus to the Platycrinidse, which according to our classification would 
i] | ' ( place the one among the Larviformia and the other among the Camerata. 
ih i) " We do not see how this can possibly be the case; we believe that Cocco- 
K | | } crinus is a true Camerate Crinoid, which passed the Larviformia stage in early 
Ween life on the introduction of perisomic plates. The genus holds a similar re- 
eal | | lation morphologically toward Platycrinus to that of the recent genus Holo- 
| pus toward Hyocrimus, whose orals have been carried inward by increased 
perisome. 
In Part II. of the Revision we referred the doubtful genus Cotyledono- 
crinus to the Platycrinide, but have since found it to be identical with 
Dichocrinus. 
In descriptions of the Platycrinide and Hexacrinide we sometimes use 
the term “interradials” for the lowest plates between the rays, because, as 
already stated, they are neither exclusively interbrachial nor interambulacral, 
but partake of the character of both; that is, the same plate often belongs 
partly to the dorsal cup and partly to the tegmen. | 
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