206 s. GOTO : 



Mouth-plates. — The month-plates are comparatively long and 

 narrow, being about 13 mm. in a specimen with K=: 2 05 mm., and 

 enclose between them a tolerably large space coverved over with 

 a membrane (PL I, fig. 10). Each plate bears some 32-40, 

 irregularly arranged spines of various sizes. The exposed surface of 

 each plate is a scalene triangle, of which the longest side faces 

 the fellow plate and the shortest side the mouth. One can 

 make out a series on the longest side of the triangle, con- 

 sisting of some dozen, somewhat large spines, of which the one 

 at the mouth end is usually larger than the others ; on the shortest 

 side there are usually four or five spines, of which the innermost 

 one is common to this and the first series ; the remaining side is 

 subdivided into two portions by a short projection at a point 

 corresponding to the furrow end of the first adambulacral plate, 

 and on this side there are some twenty spines, most of which are 

 small, and of which the one at the mouth end is common to this 

 and the preceding series. The remaining spines, which are of 

 various sizes, are mostly borne on the adorai half of the plate in 

 the area enclosed by the three series mentioned above. 



Ventrolaterals. — The ventrolateral area is very distinct, and 

 there is a series of plates extending about two-thirds or more into 

 the arms. In the area limited by the second inferomarginals on 

 either side, there are some twenty-five plates, which are mostly 

 small and leave soft membranous areas between. The plates pre- 

 sent convex surfaces covered with pointed conical spines, one or 

 two of which in each plate are usually larger than the others. 

 These larger spines occasionally tend to form a series with the 

 large inferomarginal spines, especially at the base of the arms ; 

 but they are very much smaller. 



