CRINOID GENUS SCYPHOCRINUS 5 1 



to require detailed comparison. Its most emphatic characters are the flask- 

 shaped calyx, swollen interbrachial areas, and extremely large size — all of 

 which are conspicuously shown in the unusually fine material now in my hands 

 as the result of Mr. Pate's collecting in 191 5. There are about 35 specimens, 

 from four localities within a limited area in Hardin County, Tennessee, several 

 of which by dint of hard cleaning have been completely freed from the matrix; 

 none have the arms preserved, but in several the secundibrach series is intact 

 in one or more rays up to the bifurcation. The size is remarkably constant at 

 a height and width of about 75 mm. or more, with a contraction of 20 to 25 mm. 

 above the strongly bulging interbrachial zone ; but a single specimen was found 

 of materially less size than that stated. 



The contour, ventricose in the middle, contracted and cylindrical above, 

 is similar to that of 6\ pybumensis, but it is much more pronounced in this 

 species. It is chiefly caused by the swollen condition of the interbrachial 

 areas, projecting in some specimens as much as 10 or 12 mm. beyond the plane 

 of the primibrachs, which lie deeply and abruptly depressed between them, as 

 if sunken into the calyx wall. 



The number of secundibrachs is a good character as distinguished from 

 that in S. elegans, being quite constantly about 12 or 13 in the specimens where 

 they can be counted — the smaller number according with the less elongate calyx. 

 The interbrachial pavement, being in the weaker part of the calyx, is complete 

 in but few of the specimens; so far as seen it is rather smooth, with low con- 

 necting ridges and shallow pits, which so strongly modify the plates that the 

 fixed pinnules are with difficulty identifiable. In one specimen they are quite 

 plain on the interior, with traces of ambulacra toward the distal ends. 



The short, pustulose elevations in the center of many of the plates, while 

 generally present, are somewhat variable, and upon a set of five specimens 

 from a different locality from the others they are wanting; but the form is 

 otherwise indistinguishable from the prevailing type. 



The Camarocrinus bulbs found in the pratteni beds are in size commen- 

 surate with the dimensions of the calyx, far exceeding those of any other 

 horizon or locality. Many of them are 150 mm. or more in diameter and almost 

 as high, and none were seen less than about 100 mm., which is the usual 

 maximum for those of other species. The average diameter in 12 specimens 

 is 125 mm., while the average of 70 specimens from the clay beds below is 

 75 mm. It is also observed that the principal root members and their connect- 

 ing pavement stand at an acute angle toward the stem, forming a pyramidal 

 or conical mass within the collar, whereas in the other specimens the floor is 

 usually almost horizontal. Also the sinus between the lobes is usually more 

 sharply indented than in the others. 



8 



