1 74 THE DEPTHS OF THE SEA. [chap. iv. 



perisom. The plates of the disk are soldered 

 together, so as to form a close mosaic (pvaelov). 

 The mouth-papillae are fused into two lines, their 

 number being only indicated by grooves. The 

 lateral arm-plates are united together above and 

 below, the upper and lower arm-plates are reduced 

 to mere rudiments, and there are no tentacle pores 

 beyond the first arm-joints. 



Fig. 34.— Dorynchus thomsoni, Norman. Once and u half the natural size ; everywhere in 



deep water. 



In our new species, which I name provisionally 

 Ophiomusium lymani, the diameter of the disk is 

 28 mm., and the length of each arm 100 mm. in 

 large specimens. The two lateral arm-plates, fused 

 together above and below, form complete rings, their 

 distal edge notched on each side for the insertion of 

 seven arm spines, of which the lowest is much longer 

 than the rest. The dorsal arm-plates are small and 

 diamond-shaped, let in between the lateral arm- 

 plates at the distal end of their upper line of 



