160 Proceedings of the Royal Physical Society. 



While the species has not hitherto been recorded from the Mergui 

 Archipelago, it has been found at the Andaman Islands, and its distribution 

 is as wide as its forms are various. 



(4) Ophiocoma scolopendrina (Lamarck). 



The species is represented by a solitary example from each of two 

 adjacent stations. 



So many variations of this species have already been described, that it must 

 seem superfluous to add to the perplexities of the systematist by further 

 detailed redescription. Both my specimens have a disc-diameter of 19 mm. 

 and an arm-length of over 110 mm. They show that: (1) the variation in the 

 distribution of the surface granules has not the geographical significance which 

 a reading of Koehler's (1898) description (loc. cit., pp. 78, 79) would suggest, 

 for while one of my specimens agrees with his description of examples from 

 the Laccadive Islands, in that the granulation is confined to the dorsal sur- 

 face, the other agrees with the variation usually described by authors in which 

 the ventral interbrachial spaces also bear granules ; (2) the alternation of 

 three and four spines is not carried out with perfect regularity, and near the 

 base of the arm a series of five spines occurs occasionally ; (8) the tentacle- 

 scales may be continued in pairs, even to the tip of the arms, and even where 

 a series of single scales is the rule the continuity is occasionally broken by the 

 occurrence of a pair. 



Localities. — St. XIII., Shore of Maria Island, 8 to 10 fathoms, rock and 

 sand (one example). St. XIV., Bushby Island pearling ground, shore to 21 

 fathoms, sand and mud (one example). 



The species is widely distributed over the Indian Ocean and the Pacific 

 Ocean, from Mozambique to the Fiji Islands. 



(5) Ophiocoma valenciae Midler et Troschel, 1842. 



There are thirteen well-preserved examples of this species from three 

 nearly adjacent stations. 



The disc-diameter of a fair-sized specimen is 18 mm., and the arm-length 

 is over 100 mm. The disc is closely covered with small granules, and is 

 yellowish-brown, while the arms are straw-coloured, often ringed with brown 

 on the dorsal surface at intervals of four or five plates. There are generally 

 six arm-spines near the disc, further out five, and for two-thirds of the arm- 

 length there are only four. The third and fourth arm-spines are the longest. 

 Most of the specimens have two tentacle-scales on the first two vertebrae, and 

 thereafter for the whole length of the arm only one, large, flat and oval shaped. 



