194 KANSAS UNIVERSITY SCIENCE BULLETIN. 



in this position. Hill' and Bather* both tried to obtain some 

 idea of the internal construction by dissecting, and removing 

 the plates, but with no success ; while Bather says of the ca- 

 lyx, "the dorsal cup alone is known to us." 



By referring to plate IX, figure 1, in which specimen No. 

 1 is shown natural size, it will be seen that the calyx was 

 very little distorted by the flattening out, and that the base 

 is nearly in the center of the specimen as preserved ; and al- 

 though incomplete it shows a base, dicyclic in form, com- 

 posed of five basals, five very small, irregular infrabasals, and 

 a centrale. Enough of the cup is preserved to show plainly 

 the structure and course of the nerve strands from the outer 

 margins of the basals to the second secundibraclis. 



There is a well-defined grooved ring, pentagonal in shape, 

 which joins together the nerve grooves that radiate from the 

 basals at the center of the radials. ( PI. X, fig. 2.) 



Specimen No. 1, plate IX, is the most instructive one ex- 

 amined, and shows the internal part of the calyx. This has 

 a dicyclic base, with small, irregular infrabasals. 



There are seven distinct but very small nerve grooves, 

 three from each right and left half of the two adjoining ba- 

 sals, and a middle groove, a little the widest, which is in a 

 direct line with each interbasal suture. A single groove, 

 commencing at the basi-interradial suture, forking at the 

 level of the basals, joins the set of grooves at the basi-radial 

 suture, from where they all converge to a center in the mid- 

 dle of the radial plate, when they join the corners of the 

 pentagonal ring commisure encircling the basals. The junc- 

 tions of the radials are also connected at the sutures by four 

 small grooves, two on each side of the ring commisure. The 

 nerves leading up into the arms, as far as the primabrachs, 

 are carried in four grooves (see pi. IX, fig, 2) , which are en- 

 circled in shallow diamond-shaped pits, radiating from the 

 pentagonal ring at the center of the radials. The pits con- 

 taining the nerve cords must have been a receptacle for a 

 bunch of muscular ligaments, having its main points of at- 

 tachment at the center of the plates, the nerve cords folio w- 



3. Kan. Univ. Quart. 1894, vol. Ill, No. 1. 



4. A Morphological Study of Uintacrinus, Proc. Zool. Sue. Loi.d., vol. 1S95, p. 979. 



