396 PALEONTOLOGY OF ILLINOIS. 



MEGISTOCRIKUS PARVIROSTRIS, M. and W. 



PI. 6, Fig 7. 

 Megistocrinus parvirostris, MKEK and WORTHEN. Proceed. Acad. Nat. Scl, Phila., 1869, p. 165. 



BODY rather small, of the usual short cup shape, about 

 one-fourth wider than high. Base nearly even with the 

 surrounding first radial and first anal pieces. First radials 

 near one-third wider than long. Second radials a little 

 smaller than the first, hexagonal in form. Third radials 

 as wide as the first, but shorter, pentagonal or hexagonal, 

 and each supporting on each superior sloping side two bra- 

 chial pieces in direct succession, upon the last of which 

 rest two or three series of double alternating pieces before 

 the commencement of the free arms, making two arm 

 openings to each ray, or ten to the entire series. First 

 anal piece wider and a little shorter than the first radials, 

 supporting three smaller pieces in the next range, above 

 which there are four or five in the third, and five in the 

 fourth ranges, which latter connect with numerous very 

 small pieces forming and surrounding the little short pro- 

 boscidiform opening. First interradials about as large as 

 the second radials, and bearing two smaller pieces in the 

 second range, three in the third, and two or three in the 

 fourth, with a few minute pieces in the latter. 



Vault a little convex, composed of moderate sized, con- 

 vex or tuberculiform pieces, the largest and most promi- 

 nent of which is in the middle, and the others surrounding 

 it, while a few minute pieces are intercalated between and 

 around the latter, particularly on the anal side. Anal 

 opening in a short, little proboscidiform protuberance, 

 placed entirely below the horizon of the arm bases, and 

 directed a little obliquely downward. Body plates, except- 

 ing the small ones, connected with the opening, all rather 

 tumid, and separated by excavated sutures, somewhat in- 



