182 
PALAEONTOLOGY OF NEW-YORK. 
Pleurocystites ( Billings). Body inequilateral : basal plates six; one side com¬ 
posed of large plates, the other of small plates. Apicial range bearing two 
arms. t 
There appears to be some analogy between this genus and Anomalocystites. 
Several species : Lower Silurian. 
Malocystites ( Billings). Allied to Cryptocrinus. Basal plates three, with several 
ranges of superior plates. 
Lower Silurian. 
Anomalocystites ( Hall, p. 132). 
A. cornutus, A. disparilis : Upper Silurian. 
Agelacrinus ( Vanuxem, 1842 ; Forbes, 1848). Mr. Forbes describes the Agela- 
crinus as a many-plated body, having fine serpentine grooves radiating from 
the mouth, in which lie the appressed arms. Ovarian pyramid in one of the 
spaces between the arms. 
A. hamiltonensis, A. lucliianus : Devonian and Lower Silurian. 
Hemicystites ( Hall). Body flattened, composed of imbricating scale-like plates : 
five double ranges of elevated plates proceed from the centre towards the 
margins, in the broadest space between which is placed the ovarian aperture. 
Attached to other bodies. 
This genus has been usually referred to Agelacrinus, but it does not correspond with that 
genus as described by Forbes. Other species may perhaps show that the Lower Silurifh, 
Upper Silurian, and Devonian forms can be united in a single genus. 
if. parasiticus. 
Heterocystites ( Hall ). Basal plates four ; second range ten, with intercalated 
smaller plates, and, above this, numerous smaller plates. 
The relations of this fossil have not been fully determined ; but from the irregularity of 
its plates, it does not appear referable to the Crinoidem. 
if. armatus : Upper Silurian. 
