CLARK: CRINOID FAMILY PLICATOCRINIDAE 499 



Anomalocrinidae, Cremacrinidae, Catillocrimdae, Belemnocrinidae, 

 Dendrocrinidae, Crotalocrinidae, Cyathocrinidae, Botryocrinidae 

 and Poteriocrinidae — cannot fail to give the impression that there 

 is certainly more than a superficial similarity between these types 

 and the Plicatocrinidae. As an interesting point it may be noticed 

 that the systematic interrelationships within the family order 

 Inadunata are decidedly heterogeneous, and the same character 

 is clearly reflected within the family Plicatocrinidae. 



While the Phcatocrinidae, broadly speaking, may be said to 

 agree perfectly with these families collectively — that is to say the 

 characters presented by the component species may all be matched 

 in the order Inadunata and in no other order — the family cannot 

 definitely be assigned to any certain position. Therefore the 

 most logical position for the Plicatocrinidae appears to me to be 

 within the order Inadunata, at the end of the series of families, 

 beyond the Poteriocrinidae. 



Long ago (1899) Dr. F. A. Bather reached the conclusion that the 

 Plicatocrinidae fwhich he divided into Plicatocrinidae and the 

 Hyocrinidae) were really inadiuiate forms, and he accordingly 

 included them in the Inadunata, which he considered as compris- 

 ing the Hybocrinidae, the Stephanocrinidae, the Heterocrinidae, 

 the Calceocrinidae, the Pisocrinidae, the Catillocrinidae, the 

 Zophocrinidae, theHaplocrinidae, the Allegecrinidae, theSynbatho- 

 crinidae, the Belemnocrinidae, the Plicatocrinidae, the Hyocrinidae 

 and the Saccocomidae. 



Of the four great orders of crinoids, two, the Camerata and the 

 Flexibilia, range from the Ordovician thru the Carboniferous. 

 The Inadunata began in the Ordovician, one (possibly two) 

 families persisting to the Permian, and one to the Trias, in which 

 horizon the stalked pentacrinites were already developed. The 

 Articulata began, so far as we can ascertain, in the Trias, and all 

 of the fossil types (excepting only the Thiolliericrinidae and the 

 Eugeniacrinidae) persist in the recent seas. It is thus not at all 

 surprising that we should find in the recent seas, in addition to the 

 dominant Articulata, a remnant of the Inadunata. 



