SCYLLARTJS SCXTLPTUS, LATR. — ■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 tirst 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 



