58 PALEOPNEUSTES CRISTATUS. 
tubercles in the interambulacral areas near the abactinal system, and the 
coarser tuberculatiou of the odd anterior groove above the ambitus ; also in 
having a larger number of primary plates. No part of the anal system or 
of the actinal system was found among the fragments. 
Paleopneustes cristatus A. Ag. 
Off Havana, S. side of Cuba, Lesser Antilles. 56-450 fathoms. 
Most cuiiinion to the leeward of the West India Islands, between 90 and 150 fathoms. 
For list of Stations, see Bull. M. C. Z., VIII., No. 2, p. 81, 1880. 
PI. XXI. 
A number of specimens of this species have been collected by the Blake, 
which are interesting as throwing additional light on tlie variability of the 
so-called lateral fasciole of this genus, and in showing the changes due to 
growth. Thus far only large specimens of this genus had been described, 
both from the Hassler and the Challenger expeditions. I have added to 
the figures of two of the principal stages of growth given on Plate XXI. 
Figs. 6-14, details of the actinostome (Fig. 5), of the apical system (Fig. 3), 
of the termination of the lateral petaloid ambulacra (Fig. 1), of the edge of 
the test near the ambitus from the abactinal side (Fig. 2), taken from a large 
specimen of this species measuring nearly 150 mm. in length and SO mm. in 
height, as these details could not be very clearly .seen in the photographic 
illustrations of this species in the Memoir on the Echini of the Hassler 
Expedition (PI. IV. Figs. 1-3, 111. Cat. M. C. Z., No. 8). 
A small specimen measuring 45 mm. in length (PI. XXI. Fig. 7) differed 
from the specimen figured in the Hassler Echini merely in size, and in 
having an indistinct lateral fasciole extending obliquely from the abactinal 
end of the anal system to the edge of the test, reaching the ambitus at the 
anterior lateral ambulacra, and extending faintly across the anterior part 
of the test along the ambitus. See Plate XXI. Fig. 7, and Fig. 8, which 
shows a small part of this fasciole close to the ambitus across the anterior 
ambulacral area. This can hardly be termed a lateral fasciole ; it reminds 
us of a similar fasciole in Calymne, and it is difficult to decide in these cases 
whether this single fa.sciole .should be called peripetalous as it passes across 
the posterior extremity of the test above the anal system, or a lateral 
fasciole occurring isolated from a peripetalous one ; or whether it represents 
a rudimentary stage of the peripetalous fasciole, not crossing the ambulacra 
