114 BRITISH PALEOZOIC ASTEROZOA. 



there is a deep notch which served for the attachment of the distal end of a mouth- 

 angle plate. Beyond the notch is the flat side for the articulation of the first 

 adambulacral. Five spine-bearing ridges run fanwise along the ossicle. The 

 spines have vanished, but their articular elevations may be seen. The sides of the 

 odontophor, which fits on to the neighbouring infero-marginalia, are very straight. 

 The proximal infero-marginalia are very prominent plates with surfaces usually 

 not uniformly swollen but ornamented by large irregular excrescences. Thus 

 the first infero-marginal on the left side of the arm has a prominent irregular ridge 

 on its oral surface, and the second and third show large mammillate inner projec- 

 tions. The first infero-marginal on the right side has a flat surface, but the second 



68 



69 



Text-fig. 68. — Plan of the ossicles on the oral surface of Lepidactis wenlocki. Ad., adambulacralia j 

 I.M., infero-marginalia ; M.P., mouth-angle plates ; O., odontophor ; T., torus, x 3. 



Text-fig. 69. — Wash drawing of the madreporite, odontophor (O.), and three infero-marginalia (T.M.) of 



Lepidactis wenlocki. x 6. 



and third ossicles are as on the left side. The infero-marginalia distal to these 

 form only a slight boundary to the oral surface, although a lateral view of the arm 

 shows that they are well developed. Their surface is uniformly swollen and 

 ornamented by pustules. Thirteen infero-marginalia have been counted in all, but 

 the extremity of the arm is not entirely exposed. 



Except in the proximal region, the greater portion of the width of the oral 

 surface is occupied by the adambulacralia. These differ somewhat in shape in the 

 various regions. About the middle of the arm they appear as oblong plates with 

 a uniform highly convex surface. Their inner nose-end is not visible, as the groove 

 is quite closed over. If the groove is slightly open, as it is in portions of arm iv, 

 the pointed nose is distinctly visible as figured for L. grayi. There appears to 

 have been a pustular closely-set ornament. The comb-spines have become 



