MELOGRINID^. 273 



which he afterwards proposed the genus Pycnocrinus, are young examples of 

 Glyptocrinus JDyerL The specimens have variously from nine to twelve dis- 

 tichals, but in place of having six to eight of them incorporated into the' 

 calyx, only one or two are calyx plates, the others being free. That the 

 specimens are comparatively smaller, the column stouter, the basals propor- 

 tionately larger, the interbrachials and interdistichals less numerous, the 

 arm joints higher, the pinnules stronger and placed farther apart, all indicate 

 a less mature stage of individual growth, a phase through which every 

 Glyptocrinus must naturally have passed. 



Miller defines Pycnocrinus as follows : '' Calyx cup-shaped. Column 

 round. Basals five, small, pentagonal. Primary radials 3X5. Sec- 

 ondary radials none. Regular interradials three. Arms ten, but some- 

 times dividing after becoming free. Pinnules dense and strong." This 

 description would apply equally well to any young Glyptocrinus. It must be 

 remarked, however, that both of Miller's types have small interdistichals, 

 which he overlooked. The presence of these plates proves conclusively that 

 at least one of the distichals takes part in the calyx, and that " secondary 

 radials " are not unrepresented in those specimens, as Miller supposed. 



Horizon and Locality. — Found associated with the two preceding species 

 at Cincinnati and other places. 



Type in the collection of S. A. Miller. 



Glyptocrinus ramulosus Billings. 

 Plate XX. Figs. 5a, I. 



1856. E. Billings; Canadian Naturalist and Geologist, No. 1, p. 54; also Geol. -Surv. of Canada (Rep. of 



Progress), 1857, p. 258, and 1859, Decade IV., p. 57, Plate 7, Pig. 2« and Plate 8, Pig. 1. 

 1881. W. and Sp. ; Revision Palaeocr., Part II., p. 189. 

 1883. S. A. MiLLEii ; Journ. Cincin. Soc, Nat. Hist., p. 234. 



A large species. Dorsal cup obconical, somewhat rounded at the base. 

 Costals and distichals remarkably uniform in size ; also the palmars propor- 

 tionally large. Plates almost flat and without any markings, except a con- 

 spicuous, obtusely angularridge passing up the rays, occupying nearly one 

 half their width. 



Basals small, only the upper angles visible from a side view. Eadials 

 somewliat larger than the costals, as long as wide. .Distichals six, exception- 

 ally seven ; the proximal one as long as the costals, but a little narrower; 

 the succeeding ones smaller. There are fixed pinnules from the second, 



35 



