NO. 3 ON THE FOSSIL CRINOID FAMILY CATILLOCRINIDAE 23 



that the correlation of these two characters, size and number of arms, 

 within the Hmits above stated, is constant for the several species, 

 which are at the same time strictly limited in their stratigraphic 

 position. 



Stated in tabular form, the relation in this respect of the species, 

 to which for further comparison I add the data for the Devonian and 

 Permian forms, is shown on page 22, maximum and minimum figures 

 of size being given with the corresponding number of arms. 



The column has the tapering proximal enlargement of thin plates 

 that is seen in many of the Flexibilia ; and the top columnal is almost 

 as large as the entire base, burying the greater part of its plates and 

 thus producing a condition favorable to the atrophy of infrabasals. 

 From the end of the tapering cone distal wards it is long and slender, 

 terminating in a pointed root adapted to quiet conditions in the 

 soft ooze. 



Catillocrinus ranged through the long time interval of the Lower 

 Carboniferous without any material change in the shape and relative 

 proportions of its radial plates, except in the latest species on the 

 eve of extinction. It is now a singular fact that when this specialized 

 type, having run its course and become extinct in the seas which pro- 

 duced the sediments of the American continent, appears in another 

 continent unconnected with this, it should be in a form which in re- 

 gard to its radial structures reverts to the plan of the European 

 Devonian, while in regard to the character of the base it takes on the 

 plan of the American Lower Carboniferous — thus combining two 

 of the leading characters of its widely separated predecessors. 



RESUME OF CHARACTERS 



For convenience of reference, I will add a resume of the characters 

 showing the relation of the genera and species of this family, with 

 citation of the principal pertinent literature. 



Family CATILLOCRINIDAE 



Wachsmuth and Springer, Rev. Pal. pt. 3, 1886, p. 267. — Bather, Crin. Gotl., 

 1893, P- 25 ; Lankester ZooL, 1900, pt. 3, p. 150. — Jaekel, Crin. Deutschl., 

 1895, p. 44. 



Inadunate crinoidea, highly speciahzed ; with unequal radials all 

 in contact, two much larger than the other three, greatly thickened 

 at the distal face, traversed in a dorsoventral direction bv food 



