176 



DISCOVERY REPORTS 



The distal pinnules have side- and cover-plates, two or three pairs to each segment, 

 along the ambulacra. The drawing (Fig. 13 c) is of the single preparation made; in it 

 the cover-plates are displaced, being pushed back so as to overlap the side-plates. 



Fig. 13. Isometra lineata. a, proximal part of a ray, x8. b, z. genital pinnule, P^j, x 16. c, side- and 



cover-plates of a distal pinnule, x 66. 



The latter are rods with branching and reticulate ends. The cover-plates are of a 

 beautiful bush-shaped form: the narrow base — the root-like part — ^is connected with 

 wide-spreading fan-like branches by a short stem which is always narrow and usually 

 not perforated. Some of the tentacles contain knobbed spicules. 



