CRINOID GENUS SCYPHOCRINUS 39 



The bi-convex chambers in this stem are similar to those in the proximal 

 part of the stem of Apiocrinus (see de Loriol, Pal. Franchise, Crinoids, vol. i, 



pl- 34, fig- 3)- 



Among the numerous testes indetermines figured by Waagen and Jahn 



the various stem characters above described are shown in profusion. 



The terminal bulbs (Camarocrinus) are large, but all much flattened; 

 some of them in this condition are 13 cm. in diameter. Since for the reasons 

 already explained the side exposed upon the slabs is the lower or non-stalked 

 side as it rested in the sea bottom, and the stalked side is invariably buried in 

 a mass of stems, arms, and pinnules, compressed into a limestone matrix, we 

 do not in any case see the actual stem attachment. Some indications of the 

 branching roots appear in a few places, but nowhere sufficiently well preserved 

 for intelligent study. The bulbs are seen to be divided into compartments as 

 usual, and were probably generally similar to those found elsewhere. But 

 comparing specimens of Camarocrinus from other localities in which the stem 

 attachment is well preserved, and which are associated in occurrence with the 

 calices of Scyphocrinus in large numbers, it is now very interesting to note that 

 the size of the stem and form of the axial canal at the distal end are precisely 

 what we should expect to find in connection with the stem above described. 

 In upwards of 75 specimens of Camarocrinus bulbs from Tennessee, ranging 

 from minimum to maximum size, all preserving the stem attachment, I find that 

 the stem at the distal end varies from 2 mm. diameter in the smallest to 9 mm. 

 in the largest — in those of medium size being about 5 to 6 mm. ; and in none 

 of those of maximum size does the stem equal in diameter that of the proximal 

 columnals in specimens of 5". pratteni found in the same beds. In the 5". pyburn- 

 ensis locality the stem attachment of the largest Camarocrinus does not exceed 

 5 mm. in diameter, while that of average sized calices of that species is 9 mm. 

 In all cases the canal is stellate and relatively small, like that of figure 6 of 

 Plate V. 



Types. — The specimen described by Zenker is in the University of Leipzig, 

 and those by Waagen and Jahn are in the Bohemian Museum at Prague. The 

 American specimens here figured are in the author's collection in the U. S. 

 National Museum. 



Horizon and locality. — In America, Helderbergian ; Bailey limestone, 

 perhaps equivalent to the New Scotland formation. A single imperfect speci- 

 men among the collections from Hardin County, Tennessee, may belong to 

 this species. Otherwise its occurrence is limited to the Cape Girardeau, Mis- 

 souri, region — although it is likely to be found in the same beds farther east- 

 ward, in Illinois, where the stems have been seen. 



