MELOCRINID^. 277 



arranged in one of the specimens: 1, 2, 3, 3, 3, 3, 3, 3, 4, 4 ; the latter: 

 1, 2, 3, 3; 3, etc. The anal side contains three plates in the second row, and 

 there are other extra plates above. Nothing is known of the ventral disk or 

 anal opening. Column sharply pentangular ; the nodal joints the longest, their 

 edges flattened (not convex) -, internodal joints short and angular in the 

 upper part of the stem, but gradually growing as large as the nodal ones ; 

 axial canal wide and slightly pentalobate, the lobes disposed radiallf/, in the 

 same direction as the outer angles of the stem. 



Horizon and Localiiy. — Upper part of the Hudson Eiver group ) at Mor- 

 'row and Waynesville, 0. 



Tyjpes in the collection of Mr, F. L. Fornshell. 



RemarJis. — It is with some hesitation that w^e place this species under 

 Git/ptocriniis, It differs from all other species of the genus in the pentangular 

 stem, and the radial position of its axial canal, a feature in which it is at 

 variance with all other known monocyclic Palaeocrinoids. That it actually 

 has no infrabasals, we ascertained from a fragmentary specimen by exposing 

 the inner floor of the basal cup. It has in the centre a large pentangular 

 open space, whose angles are pointed to the interbasal ■ sutures, taking the 

 same direction as the angles of the stem. A somewhat similar departure 

 from the rule is claimed to exist in the recent genus Pentacriniis, in which^ 

 however, stem and canal are m^^rradial. 



PERIGLYPTOCMNUS W. and Sp. (nov. gen.). 



Closely allied to Gli/ptocrinus, but having larger basals and well developed 

 hiserial arms ; the arms of Gly^ptocrhms being described by all writers as uni- 

 serial. The only two species known to us are our new species Periglypto- 

 erinus Billing si, which we make the type of that genus, and P.priscus, which 

 was described by E. Bilhngs as a Olyptocrinus. Fragments of a third species 

 are found in Alexander Count}^, Ills. 



Distribution, —Black Eiver shale, and Trenton hmestone of Canada. 



Periglyptocrinus Billingsi w. and Sp. (nov. sp.). 



Plate XXI. Figs, la, h. 



A beautiful and highly ornamented species. Dorsal cup elongate-obcon- 

 ical, higher than wide, somewhat depressed at the interradial and interdis- 



