17 



3. Astropecten mauritianus, Ciray. 

 Perrier, loc. dt., v. p. 279. 



Localities. — Frequent on pearl banks throughout the Archipehigo, in 5 to 25 

 fathoms, sand and rock. 



R^lll r=21-5 ^=81 >-=19. 



Undoubtedly this species is very closely allied to A. Hempnchii, M. & T., 

 despite de Loriol's belief that the two species cannot be confused (M^m. Soc. 

 Phy. Hist. Nat. Gen., t. xxix., No. 4, p. 74, and pi. xxi.). He lays stress 

 on the absence of supero-marginal spines in the angles of A. Ifemprichii and 

 their presence in A. mauritianus, but this, as Jeffrey Bell has pointed out, 

 is not a reliable character in Astropecten. It will not be surprising if the 

 two species prove to be one and the same. I have named the Mergui 

 specimens after careful comparison with specimens in the British Museum. 



A new record for the P^astern Indian Ocean, but Dr Anderson collected 

 A. Hemprichii in the Mergui Archipelago. 



4. Astropecten zebra, .Sladnn. 



Slailen, '•Challenger" Reports, xix. p. 212, and pi. xx.wi. figs. .3 ami 4 ; 

 pi. xxxix., figs. 7 to 9. 



Localities. — IX., Courts Island to Bentinck Island, 12 to 26 fathoms, coral 

 and sand ; XXV., Gregory Group, 4 to 14 fathoms, sand and broken shell. 



Four specimens, the two larger of which are each in process of regrowing 

 an arm. 



i2=2G /• = 7-.5 A' =30 r = 8 E = 25 r=7 A' = 16-5 r = 5-5. 



A slight prominence in the centre of the upper surface of the disc appears 

 as a conical beak in the smaller specimens; it is most prominent in the 

 smallest. Of the supero-marginal plates, as many as tiie eight innermost on 

 either side of each arm may bear spines, but of these the last two are very 

 rudimentary. In the smallest specimen, one or two of the supero-marginals 

 on each side of the median interradial line bear spines. Even in the larger 

 specimens, however, the number of spines is variable, bearing out .Jeffrey 

 Bell's contention as to the absence of value of these in classification (Hornell 

 and Herdman, Ceylon Pearl Oyster Fisheries Report, ii. p. 149). Bell thinks 

 {loc. cit.) that A. zebra and A. Hemprichii are identical. They certainly 

 approach one another very closuly in their characters, but those whicli I'ell 

 figures (from photographs) as^l. Hemjiriihii seem to be A. zehra and apparently 

 were thus named by Sladen. 



Known previously from Torres Strait and Ceylon. 



