248 
in single series) longer on one side than the other, and often 
wedge-form, with pinnulse originating on the longer side * 
Brachial plume closely apposable. 
ScAPHiocRiNus LATiFRONS (Austin), Sladen. 
Poteriocrinus latifmis, Austin, Monog. Rec. and Foss, 
Crinoidea, p. 82, pi. 10, fig. 4. 
This crinoid presents many resemblances to Scaphio- 
crinus scojparius, Hall (Report Geol. Surv. Iowa, vol. i., pt. 2, 
palaeont, p. 680, pi. 25, fig. 3). Our English specimen, 
however, difiers mainly in the greater length of the second 
(or free) radials, and the proportionally smaller size of the other 
plates of the calj^x. MM. Austins' figure does not indicate the 
wedge-shaped character of the brachial elements so pronoun- 
,cedly as the American figure. S. latifrons possesses a greater 
number of plates in the secondary radials, and the arm- system 
or " plume " is more closely constrict and drawn together, in 
consequence, presumably, of the smaller development of 
pinnula). In 8. latifrons the brachial plume is much more 
largely developed, and more robust in proportion to the size 
of the calyx-body than in S. scoparms. 
Zeacrinus (Troost), Hall. 
Calyx, broad and gibbous; contour subglobose; base 
always rotund, more or less impressed, often deeply concave. 
Basal plates, five, usually small and hidden by the column 
in the deep cavity of the base. 
Sub-radials, five, pentagonal or hexagonal (rarely with six 
sub-radials). 
First radials, five, pentagonal. 
Free radials, one to each first-radial plate (and one or two 
additional intermediate plates on the anterior ray); pen- 
* Sutures between the radial and arm plates usually more or less gaping 
exteriorly, with the edges of the plates rounded, as if the space had been filled 
with some cartilaginous or muscular substance during the life of the animal. 
Pf. Hall, Eeport Geol. Surv. Iowa, vol. i. pt. 2 (palacont.), p. 551. 
