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TOE VOYAGE OF H.M.S. CHALLENGER. 



examples it can scarcely be discerned at all. This is caused by a difference in the form of 

 the abactinal plates, although the circumstance is scarcely apparent superficially owing to 

 their membranous covering. The presence of this band suggests the character produced 

 by the different form of the median and lateral series of abactinal plates in Nepanthia. 



Subfamily Asterinin^e, Sladen, 1888. 



Genus Patiria (Gray), emend. Perrier. 



Patiria, Gray, Ann. and Mag. Nat. Hist., 1840, vol. vi. p. 290. 



Patiria, as constituted by Gray, was an ill-defined group, which included forms that 

 cannot be separated by any essential character from Asterina. The genus was subsequently, 

 and with great justice, limited by Perrier to one of the three sections made by Gray, and 

 comprised only two species, those named by him Patiria ocelli/era and Patiria crassa. 

 This view of the genus is the only one which can be maintained. A third species has 

 been added by the Challenger. That Patiria is very closely allied to Asterina there can 

 be no doubt ; and a young form which I have referred to the species described below 

 indicates this affinity even more closely than the adult forms, and suggests the assumption 

 that Patiria is probably immediately descended from an Asterina-like ancestor. As 

 known at present the genus is confined to the southern hemisphere ; but the locality of 

 one of the original species is unknown. 



Chorology of the Genus Patiria. 

 a. Geographical distribution : — 



Atlantic : One species between the parallels of 30° and 40° S. 



Patiria bellula, from Simon's Bay, Cape of Good Hope. 



Indian Ocean : One species between the parallels of 10° and 50° S. 

 Patiria crassa from Western Australia. 



/3. Bathymetrical range : Shallow water. 

 y. Nature of the sea-bottom : Not recorded. 



Chorological Synopsis of the Species. 



