REPORT ON THE ASTEROIDEA. 



341 



Torres Strait as belonging to this species. The major radius measures 13 mm., and the 

 form is far too small to permit of a defiuite expression of opinion as to the species. The 

 example is figured on Plate LVI. to show the strikingly Pentagonastrid character of its 

 abactinal plating at this stage of growth. 



Genus Hippasteria, Gray. 



Hippasteria, Gray, Ann. and Mag. Nat. Hist., vol. vi. p. 279. 



Goniaster (pars), Agassiz, Mem. Soc. Sci. Nat. Neuchatel, 1835, t. i. p. 191. 



Astrogonium (pars), Miiller and Troschel, System der Asteriden, 1842, p. 52. 



This well-marked genus is represented by only a single species. Several authors have 

 sought to establish distinct species on the basis of what appeared to be well-marked forms, 

 but up to the present time none of these have stood the test when compared with a good 

 series of examples. The genus as at present known is confined to the northern area of 

 the Atlantic. 



Cliorology of the Genus Hippasteria. 



a. Geographical distribution : — 



Atlantic : One species between the parallels of 40° and 80° (?) N. 



Hippasteria plana, — on the eastern side : off the British Islands, 

 Bohuslan, Finmark, Lofoten, and off the Murman coast (fide Daniels- 

 sen and Koren). On the western side : off Cape Cod, Nova Scotia, 

 and northward (Verrill). 



/S. Bathymetrical range: 30 to 150 fathoms. 



y. Nature of the Sea-bottom : Only stated in a few instances ; those recorded are Clay, 

 Gravel, and Stones. 



Chorological Synopsis of the Species. 



1. Hippasteria plana (Linck), Gray. 



Pentaceros planus, Linck, 1733, De Stellis marinis, p. 21, tab. xii. No. 21 ; tab. xxxiii. No. 53. 

 Asterias equestris (pars), Linne, 1766, Systema Naturae, ed. xiL, p. 1100. 



Asterias phrygiana, Parelius, 1768, K. Norske Vidensk. Selskabs Skrifter, vol. iv. p. 425, tab. xiv. 

 figs. 1 and 2. 



