234 DESCRIPTION OF THE SPECIES OF PTERYGOTUS 
Sculpture. 
The whole of the body rings are ornamented with a similar 
sculpture, although not equal in size or distributed exactly in the 
same way over all the segments. Curved plica, like those which 
occur on the epistoma, occupy the anterior half of each body 
segment, and are from one to two lines wide, in open semicircular 
curves upon the middle parts and anterior angles of the segments, 
but on the front edges they are nearly straight lines and much more 
crowded. 
This arrangement is nearly uniform for the first five or six rings, 
the plice ceasing rather abruptly about the middle of the segment. 
In the hinder ones they cover a larger surface, Plate V. [Plate 16] 
fig. 1, and on the under sides of all the segments (Plate IV. [Plate 
15] figs. 5, 6), they also occupy nearly all the surface, though more 
sparingly placed on the posterior half. On the 11th segment, the 
plicee reach down along the central keel, but are absent from the 
outer angles, and on the under side, fig. 3 a, they occupy a still 
smaller area; while on the caudal joint only a small portion near the 
base or insertion of the joint is marked by them. 
In the hinder rings, the tenth and the two last especially, the 
sculpture on the dorsal side is more angular ; the plice being longer 
and narrower than even on the ventral side, where it is usually more 
angular than on the upper surface. As inattention to this point 
might mislead in comparing with other species (P. gigas, for instance, 
Plate VIII. [Plate 19]), it is of consequence to note this difference in 
the ornamentation of different portions. 
Appendages. 
«lntenne, Plate VI. [Plate 17] figs. 4, 6—They were of great 
size. Plate VI. [Plate 17] fig. 5, shows the largest we have seen, 
but a somewhat smaller size (fig. 4) is not at all unfrequent. There 
are four joints, including the free terminal claws. 
Of the first articulation only short fragments remain, it is 
narrower than the second, which is linear, scarcely contracted at 
either end, and in the largest specimen must have been four 
inches and a half long and one inch and a quarter broad. The pen- 
ultimate joint, which is produced into the fixed claw of the chela, 
is rather suddenly swelled, and increases in width outwards to the 
insertion of the terminal joint. The produced portion is fully four 
inches long, rather narrowed at its insertion (so as to be a little fusi- 
