260 THE VOYAGE OF H.M.S. CHALLENGER. 



most part of the ray may bear a single pedicellaria, but along the ray they are either naked 

 or bear only small cilia-like, but invested, spinelets. 



The madreporiform body is hidden by paxillae. 



Colour in alcohol, a bleached ashy or yellowish white. 



Young Phase. — A small example was obtained at Station 188 in company with a 

 larger specimen, which seems to me in every way identical with the type form. About the 

 small example, however, which has a radial measurement of 18 mm., I feel much doubt as 

 to whether it belongs to this species or to a new one. The actinal characters conform 

 closely enough with those of Luidia forjicifer, but on the abactinal surface the paxillae 

 are furnished with a robust central papilliform granule or incipient spinelet, of which no 

 trace is found in the adult forms above described. Without more material to furnish a 

 clue as to the intermediate stages (if such really exist), I am unable to express a definite 

 opinion on the young example under notice. 



Localities. — Station 187. Booby Island, Torres Strait. September 9, 1874. Lat. 

 10° 36' 0" S., long. 141° 55' 0" E. Depth 6 fathoms. Coral mud. Surface tempera- 

 ture 77°7 Fahr. 



Station 188. In the Arafura Sea, near the entrance to Torres Strait. September 10, 

 1874. Lat. 9° 59' 0" S., long. 139° 42' 0" E. Depth 28 fathoms. Green mud. Surface 

 temperature 78°'5 Fahr. 



Remarks. — This species may be distinguished by the form of the rays, by the 

 character of the paxillae, and by the armature of the adambulacral and infero-marginal 

 plates. 



Family Pentagonasteridae, Perrier, 1884. 



The family Goniasteridae, as defined by M. Perrier 1 in 1875, has been recently divided 

 by him " into four families, the Pentagonasteridae, Pentacerotidae, Antheneidae, and Gym- 

 nasteriidae. With this step I entirely concur, reserving only some doubt about the validity 

 of the Antheneidae as a group worthy of family rank, its credentials appearing to me to be 

 more or less artificial. 



The limits of the genera included iu the Pentagonasteridae have been critically and 

 justly discussed by Perrier. 3 I have, however, ventured to differ from him in that I have 

 limited the term Astrogonium to those species for which he has proposed to restore the 

 generic name of StephanasterS The reasons for this step, which seems to me unavoidable, 

 are discussed on p. 285. I have furthermore felt obliged to separate a small group of 

 species distinguished by definite structural characters from the other Pentagonasteridae, for 



1 Revis. Stell. Mus., p. 25 (Archives de Zool. exper., 1875, t. iv. p. 289). 



2 Nouv. Archives Mus. Hist. Nat., 2e Se>ie, 1884, t. vi. p. 165. 



3 Revis. Stell. Mus., p. 100, el seq. (Archives de Zool. exper., 1876, t. v., p. 6, et scq.) 



* Comptes rendus, 188.3, t. ci. p. 885; Ann. Sci. Nat. (Zool.), 1885, t. xix., Art. No. 8, p. 30. 



