60 Proceedings of the Royal Physical Society. 



additional spine may occur near the middle of a plate ; this is more marked 

 towards the distal end. 



The colour fundamentally is brownish-grey, but the centre of the disc 

 is usually purple. There are usually three or four transverse purple bands 

 on each arm ; these extend in some cases to the ambulacral grove. 



Locality. — Type specimen: Station II., Wamizi island. Five other 

 specimens : Station I, Tunghi Bay. 



Nardoa variolata, Gray. 



Two specimens from the reefs around Matemo Island represent this 

 species. In the largest _R=65, r=ll. Neither specimen is fully mature, 

 and the number of plates on the side of each arm does not exceed 30 or 31, 

 whereas in full-grown individuals 45 is not infrequent. 



Locality. — Station IX., Matemo Island. 



Previously recorded from — Bed Sea ; Zanzibar ; Bourbon ; Mauritius ; 

 Mozambique ; Eodriguez ; Ceylon ; and Australia. 



Retaster cribrosus (von Mart.). 



This species is very abundant on the coast, and specimens from four 

 different localities are represented in the collection. 



72 = 38, r= 9; B = 4"2r. 

 .#-37, r=13; A'=3r. 



Most of the specimens are fully grown, and in some of them the arms 

 taper more than is usual in this species. In some individuals the paxillse 

 spinelets on the dorsal surface are not well developed, hut even in young 

 specimens they are never entirely absent. 



The colour of the specimens is rather unusual. Most of them are black, 

 with ashy-white ridges on the dorsal surface ; sometimes these ridges are 

 ruddy or even orange-coloured. 



One specimen has only four arms, and these are arranged symmetrically. 



Localities. — Station IT., Maiyapa Bay (near Magi-mazizi) ; Station 111., 

 Mtundo Bay (between Wamizi Is. and Kifuki Is.) ; Station VI., Kero- 

 Isyuni Bay ; Station IX., Matemo Island. 



Previously recorded from — Samoa and Philippines to Mergui ; Amboina ; 

 Tort Molle and Thursday Island, 4 fathoms (coral); Singapore; Ceylon; 

 Mozambique ; Dar-es-Salaam ; and Zanzibar. 



[Issued separately, 18th February 1910. ) 



