28 OPHIUR.E. 



it was the variety, 2 albida, of Lamarck. It had long 

 before, however, been placed aside as distinct by my friend, 

 Mr. W. Thompson of Belfast ; and I have seen it so 

 separated in several collections, under the belief that the 

 larger species was the lacertosa and this the texturata. 



The disk is round, imbricated above with smooth unequal 

 scales, a large one in the centre, surrounded by five others of 

 equal size. The scales are always larger and fewer than 

 in the last species ; and this serves also to distinguish the 

 young of the two Sand-stars from each other, though, besides 

 this distinction, the young alb Ida is much thicker and smaller 

 in proportion to its arms, than the young texturata. Op- 

 posite the base of each ray are two triangular plates, simi- 

 larly placed to those in the last species. The pectinated 

 scales clasping the rays never bear more than sixteen teeth. 

 The plates separating the origins of the rays beneath are 

 shaped like a shield, with straight sides. The rays are 

 covered superiorly by transversely ovate hexagonal scales, 

 and below by smaller plates of a similar form. The lateral 

 ray-plates bear each four or five short appressed spines. 

 The rays are three or four times as long as the disk is 

 broad. The largest disk I have met with measures half 

 an inch across. When alive the disk is generally pink, 

 with ten white spots, which occupy half of each of the ten 

 [dates opposite the ray-origins. The centre of the arms 

 is pink ; the under surface and spines white ; the cirrhi 

 and tentacula are tipped with yellow : sometimes the disk 

 is marbled with orange spots. 



When one of these creatures is put into a vessel of salt 

 water, it will remain quiet for some time, contrary to the 

 habit of the Brittle-stars, and then slowly move its arms 

 up and down. Should it be placed on its back, that posi- 

 tion appears to be very disagreeable to it ; for it inime- 



