68 
prominent ; plates arranged in fonr and perhaps live series ; if so, the central 
row much smaller than the others. Amhnlacral areas apparently three- 
eighths of an inch wide. Teeth large and strong, quite two-thirds of an inch 
in length. 
Obs . — So far as I am aware, the existence of the interesting group of 
the Perischoechinidrc has not hitherto been recognised in the Permo- 
Carhoniferons rocks of this Continent. The line, although much maltreated, 
specimen now lignred, was rescued from the debris of the Departmental 
Collection at the Garden Palace lire in 1882. Previous to this disaster a 
description of some utility might have been drawn up, hut in the present 
state of the fossil this is hardly possible. 
The portion remaining consists of rather less than the ventral half, 
v'ith the “ Lantern of Aristotle ” in situ. The test was fully fonr and a half 
inches in diameter, and must have been that of a robust individual, hut in its 
present state the ajiproximatc height cannot he arrived at. The positions of 
two of the ambulacra arc indicated by faint impressions of the plates, and 
those of the others can he fixed by measurement. The two rows of plates 
appear to have been three-eighths of an inch wide, hut all trace of the pores 
is quite lost. 
The interamhulacral plates were very large, fully half-an-inch in 
diameter, with prominent edges, and the surface between these and the 
miliary rings concave. There is, in relation to these plates, an obscure point, 
which I am not at present prepared to explain. The rows of plates in each 
intcr-amhulacral area are certainly four, hut in the middle line of the three 
best preserved areas, between the two contiguous rows of tubercle hearing 
plates, are smaller pieces devoid of tubercles. This central line of each intcr- 
ambulacrnm is also its most prominent position. The state of preservation is 
so indifferent that too much stress cannot he laid on this point, hut from 
their appearance on throe of the interamhulacra one is led to regard this 
feature as a structural arrangement. In such a case it would have equal 
value with the somewhat analagous arrangement met with in JPerischodomus, 
]\I‘Coy,* and must be looked upon as of generic importance, and a new name 
coined for its reception. The characters of the interamhulacral plates arc, 
however, so manifestly those of Archceocidaris that the specimen is for the 
* Ann. Mag. Nat. Hist., ]849, III, p. 253. 
