SCYLLAEUS SCULPTUS, LATE. — WHITELEGGE. 
159 
almost straight; all except the sixth and seventh have a prominent 
transverse denticulated ridge, which is directed backwards ; it is 
centrally situated in the first and second. In the succeeding three 
the posterior margin to which the connecting membrane is attached 
is very short, and is overlapped by the denticulate ridge. In the 
female this ridge is present, but it is smooth and much less 
distinct in all except the first segment. 
The inferior surface of the sixth segment is flat, punctate, 
smooth, with a slight longitudinal median groove, it is imperfectly 
calcified, and scarcely higher than the bounding membrane. In 
length it exceeds the two preceding, and is equal to the third ; 
the latter is shorter than the second or first, which are twice as 
long as the fourth. 
Superiorly the segments, except the first and seventh, are sub- 
equal in length. Their width gradually diminishes; the first 
measures 54 mm. across between the joints, and the fifth 
35 mm. 
The surface ornamentation consists of groups of arborescent 
patterns, and flat subimbricated scales ; the latter occur chiefly 
on the upper and on the lower posterior regions of the coxal 
plates. The former are present on the second to the fifth segments 
and disposed as follows : a narrow median group which forms the 
longitudinal keel ; on the second the keel commences about the 
middle and is continued to near the posterior margin, where it 
becomes transverse and extends nearly the whole width of the 
segment. There are two prominent groups, one on each side of 
the keel, but separated from it by a longitudinal row of two or 
more rounded tubercles. 
On the remaining somites the dendritic sculpture becomes a 
little less distinct, but the keel is longer, and on the fifth it equals 
the segment. 
The coxal plate of the second segment is very large and bilobed. 
It bears a Y-shaped impression on its surface, and from twelve to 
fourteen spines or tubercles along its margin. The front portion 
of the margin is transverse, the outer is obliquely directed back- 
wards and downwards, and terminates in a large triangular tooth. 
The margin of the posterior lobe has five rather large denticles, 
and is slightly curved forwards towards its extremity. 
The plates on the next four segments agree in having the anterior 
margin elongate, straight, almost smooth, and slightly crenate, and 
the posterior more or less curved and dentate like the second. The 
outer border, however, differs in each. In the third it is obliquely 
truncated and obscurely bi- or tridentate, the posterior denticle 
being rather large. The fourth is truncate and may be regarded 
as one broad lobe or tooth. The fifth and sixth are triangulate, 
the latter somewhat elongate 
