MR. E. A. SMITH ON A IfEW POK.M OF OPHIUEID^. 337 



nate, and a trifle longer than a lower arm-plate. Uppermost 

 spines placed at irregular intervals of two to five or even more 

 plates ; they are very large and stout compared with the others, 

 frequently lobed at the end, somewhat scabrous, and about as long 

 as the width of the arm. The colour is everywhere of a uniform 

 cream-tint ; the specimen perhaps is faded. 



I cannot give the exact number of teeth, as there is but a single 

 specimen, which would have to be mutilated too much in order to 

 ascertain it ; however, as far as can be seen, they appear to be few 

 in number, stoutish, and truncate at the ends. 



Under the microscope the arm-plates and spines are seen to be 

 delicately granulous ; and the apices of the largest spines are beset 

 with most minute prickles. 



Both the upper and lower arm-shields gradually become pro- 

 portionally longer towards the end of the arms. 



OpJiiomastix flaccida, of Lyman, in many respects closely re- 

 sembles this species ; and since it has no tentacle-scale, it will come 

 in this subgenus Aeantharachna, The chief difference in the two 

 species is in the covering of the disk. In A. Jiaccida it is " wholly 

 covered by a smooth skin," whilst in A. mirahilis the covering is mi- 

 nutely squamose and displays small naked radial shields, and the 

 margins of it are clothed with larger scales than those on the 

 dorsal surface. The form of the lower arm-plates is different in 

 the two species ; the side mouth-shields and the colour also show 

 certain differences. 



DESCRIPTION OF PLATE XVIIL 



Fig. 1 . Ophiomastix {Aeantharachna) mirdbilis. View of upper surface, of 

 natural size. 



2. View of the lower surface, also of natural size. 



3. The disk, seen from below, enlarged about twice nat. size, and showing 



the oral orifice with papillae and also form of oral and anal shields. 



4. Part of an arm seen from above, showing the form of the plates and 



the spines. About 3 diam. 

 b. Magnified view of a bifid brachial spine. 

 6. Apex of a terminally trifid brachial spine, also enlarged. 



20*^ 



