REPORT ON THE ASTEROIDEA. 405 



margin of the disk, and its margin prevents the meeting of the lateral series of abactinal 

 plates next the median radial series of the two adjacent rays. The striations are fine and 

 sharply convoluted, the general trend being more or less regularly centrifugal. The primary 

 apical plates on the disk are distinctly discernible. 



The anal aperture is excentric in position, and is closed by a few small, valve-like, 

 scutiform plates. 



Colour in alcohol, a light brownish grey on the abactinal surface, mottled with darker 

 patches of brown here and there, and with a number of the papular areas marked with a 

 much darker shade of brown, the papular areas generally being darker than the plates and 

 dissepiments, which gives a very ornate character to the species. The actinal surface is 

 a bleached white. 



Locality. — Station 186. In Torres Strait, off Cape York. September 8, 1874. Lat. 

 10° 30' 0" S.j long. 142° 18' 0" E. Depth 8 fathoms. Coral mud. Surface temperature 

 77°-2 Fahr. 



Remarks. — The nearest ally of this species appears to be Ophidiaster granifcr, Liit- 

 ken, but it is well distinguished by the six rows only of papular areas, by the great size 

 of these and the numerous papulae, by the character of the granulation and the presence 

 of the large conical tubercles, by the small dumpy pedicellarias, and by the peculiar form 

 of the outer spinelets on the actinal surface of the adambulacral plates. The triple series 

 of spinelets in the armature of the adambulacral plates recall the same intermediate 

 character between Ophidiaster and LincJcia as already noted in Ophidiaster granifer by 

 Perrier. 1 



5. Ophidiaster helicostichus, n. sp. (PI. LXIX. figs. 5-7). 



Rays five. R=130 mm. ; r=12"5 mm. R = 10"4 r. Breadth of a ray near the 

 base, 13 - 5 mm. 



Rays elongate and tapering gradually to the extremity. Disk small and slightly 

 convex. Interbrachial arcs subacute. 



The abactinal and marginal plates, which are arranged with great regularity, form seven 

 longitudinal series. The plates of the median series are rather larger than the others, which 

 are small in comparison to the size of the starfish, and all are united by broad, sharply de- 

 fined dissepiments. The surface of the plates is very slightly convex, and is covered with a 

 small, rounded, closely packed, and nearly uniform granulation, excepting round the margin 

 of the papular areas where it is extremely small. None of the plates bear large granules 

 or tubercles. Small entrenched pedicellariee of the figure-of-eight form are occasionally 

 present on the plates near the margin of the papular areas, but are not numerous. 



The papular areas, which are large and rather deeply sunken, are subcircular or oval 



1 R6vis. StelL Mus., p. 128 (Archives de Zool. exper., 1875, t. iv. p. 392). 



