GENUS ALLAGECRINUS, Carp, and Ether. 



ALLAGECRINUS CARPENTERI, Wachsmuth. 



PI. XXIX, Fig. 14. 



AUayeorinta Carpenteri, WACHSMUTH, February, 1882. 

 Bulletin No. 1, of the Illinois State Museum of Natural History, p. 40. 



The unique specimen upon which this species is founded is from 

 the collection of Prof. Worthen, who kindly permitted me to describe 

 it. It is partly imbedded in the rock, but only a small portion is 

 covered by the matrix. It consists of a two-inch column, the calyx 

 and arms. The calyx is somewhat pressed out of shape, but with 

 this exception is excellently preserved. The specimen is small, its 

 length measuring from the basal disk to the tips of the arms 80.100 

 parts of an inch, to the arm bases 16.100 parts, of which the basal 

 disk occupies only 4.100 parts. 



Specific Diagnosis: The calyx is of small size, the form is cylin- 

 dro-conical; it is composed of two rings of plates, the upper sup- 

 porting the arms. There are no interradials, and no azygous side. 

 Plates strong, without ornamentation. 



Basal disk undivided, at least without visible suture lines; it is 

 short, three times wider than high, saucer-shaped the upper side 

 but little wider than the bottom part, with very obtuse upper angles. 



Eadials 1x5, differing somewhat in width, wider at the top, 

 quadrangular in outline, but actually pentangular; axillary, with 

 very obtuse upper angles, the sloping sides slightly excavated and 

 supporting the free arms. 



Arms two from each ray, simple throughout, unequal in size, 

 some of them one-half thicker than others not tapering ; nearly as 

 thick at the distal end as at the base. The arms are constructed 



