LEPIDACTIS WENLOCKT. 115 



detached, but the short groove-spines may often still be seen on each side of the 

 groove. The anterior depressions for the muscle-attachments may also be seen on 

 a few of the ossicles on this same arm. They are not very distinct, but seem to 

 have been confined to the inner oral side of the ossicle exactly as in Lepidaster, 

 and not so deep as in that form. 



The adambulacralia become smaller both proximally and distally from the 

 median ossicles already described. The distal adambulacralia have the same shape 

 and ornament as that already described. Proximally, however, the plates appear to 

 become irregular in form. Unfortunately, owing to the disturbance already referred 

 to, their exact shape and disposition are difficult to make out. Some of the out- 

 lines presented are given in Text-fig. 68. This same disturbance does not allow 

 recognition of the mouth-parts in situ. A displaced mouth-angle plate lies near 



Text-fig. 70. — Plan of the ossicles on a portion of the apical surface of Lepidaatis wenloeki. R., radialia ; 



M., supero-marginalia. x 3. 



the madreporite, and it is very similar to that figured for Lepidaster. A few thin 

 odontophors with spines still attached may also be seen in the central disc region. 



The madreporite is a very large swollen plate lying at present entirely on the 

 oral surface. There has been considerable disturbance in the interradius where it 

 is situated, and it may originally have been somewhat oro-marginal in position. It 

 is figured together with its surrounding plates in Text-fig. 69. It lies on the 

 outer side of three plates, the odontophor and the proximal infero-marginalia, and 

 is separated from the odontophor by a fourth small plate. Its outer edges are 

 rounded, its proximal edge concave and distal edge convex. The madreporiform 

 markings are raised and remind one in their appearance of some of the " chain 

 corals." Generally, except in position, the plate is very dissimilar from that 

 observed in Lepidaster. 



Side View. — A lateral view of arm iv shows that the supero- and infero- 

 marginalia are almost opposite. Two intermarginalia are seen. The larger 

 proximal intermarginal is curious, inasmuch as it appears simply to stick on the 



