8-1 PROF. F. J. BELL ON THE [Feb. \ ( .>, 



with rounded tubercles very similar to those which are found on the 

 lophial line ; there are no spines of any sort on the inferomarginals. 



The spines of the adambulacral plates in the dried specimen have 

 been for the most part lost, as have also the granules on the ventral 

 plates. In the " type " the inner row has five not particularly 

 delicate spines ; those of the next row form a pretty stout pair, and 

 outside these there is a set of smaller and more irregularly disposed 

 spines. The ventral plates, which are distinct from one another, are 

 covered by large granules, among which may be discerned a fair 

 number of valvular pedicellarise of various sizes. 



On comparing the smaller and the larger specimen (which give 

 respectively the following admeasurements — R=52, 76 ; r—23, 31 ; 

 breadth of arm at base 25"5, 36 - 5) we see that the leading differences 

 between them are — (1) the smaller sometimes has spines on the 

 inferomarginal plates, which themselves take some share in forming 

 the sides of the arms ; (2) the number of marginal plates is smaller ; 

 and (3) nearly all the superomarginals carry nodose spines or 

 tubercles. 



We have therefore in this species a growth-character which differs 

 from that which ordinarily obtains in this genus ; but it is one which 

 can be explained by reference to the small size and rare distribution 

 of the poriferous areae, coupled with the considerable size and re- 

 sisting power of the ossicles of which the skeleton is here composed. 



Oreaster orientalis. 



Oreaster orientalis, M. Tr. p. 1 28. 



Three dried specimens of this species, the first representatives of it 

 in the British Museum, have recently been acquired from the Chinese 

 Court in the late Fisheries Exhibition, and I am able therefore to 

 give an independent description of a species which has never been 

 mentioned since the time of Miiller and Troschel. 



A triplacauthid form, with a hig'i disk and the general habit of 

 O. reticulatus, but with dorsal spines much less well developed and 

 ventral spines altogether absent. 



R=£ - 5 r. Disk elevated ; arms narrow at their base, slender in 

 portion to the disk. Lophial line well marked, but spines not long : 

 apical spines prominent, a few short spines within the apical region. 



From about 20 to 25 marginal plates, the boundaries between 

 which are not always as well marked as in most species of the 

 genus ; both sets take part in forming the sides of the arm ; in the 

 angles of the arm both sets bear spines, rather short and sharp ; 

 further out the spines are smaller and less regularly developed ; they 

 are, however, absent from the upper, and generally present on the 

 distal lower plates. Adambulacral spinulation triplacanthid : eight 

 (nine testibvs Miiller & TrOscliel) delicate short spines in the inner- 

 most row, each set separated by a lorcipiform peilicellaria ; five much 

 stouter in the middle, and two to four in the outermost row. With 

 advance in size the boundaries between the ventral plates become 

 obscured ; the granules are closelv packed and large, but always 

 remain flat, and never become produced into spinous processes ; 



