6 THE VOYAGE OF H.M.S. CIIALLENGER. 



The asterid obtained during the "Blake" dredgings and described by Perrier 1 under 

 the name of Archaster simplex, is without doubt a Parar 'chaster. It is, however, an 

 immature form, and I am unable to say from the description given whether it belongs to 

 an independent species or is the young of one of those herein described. The figure 

 given 2 is altogether unlike the smallest example of Pararchaster armatus in the character 

 of the armature both of the adambulacral and infero-marginal plates, and this appears to 

 be the only form with which a direct comparison can be instituted. The description is 

 too short to render any assistance in this case. 



Chorology of the Genus Pararchaster. 



a. Geographical distribution : — 



Atlantic : Three species between the parallels of 50° N. and 10° S. 



Pararchaster armatus and Pararchaster semisquamatus, var. 

 occidentalism off the coast of North America. Pararchaster armatus 

 is also found off the coast of Portugal. Pararchaster spinosissimus 

 off the Island of Ascension. 



Pacific : One species between the parallels of 30° and 40° N. 

 Pararchaster semisquamatus, south of Japan. 



Southern Ocean : Two species between the parallels of 30° and 70° S. 



Pararchaster pedicifer between the Cape of Good Hope and 

 Ker°;ue]en Island. Pararchaster antarcticus in the region of the 

 Antarctic Circle, near the meridian of 80° E. The latter species is 

 nearly allied to a species in the North Atlantic and also in the North 

 Pacific. 



/8. Bathymetrical range: 425 fathoms to 1900 fathoms. 



All the species excepting one {Pararchaster spinosissimus) belong to the 



Abyssal zone. Two species only [Pararchaster spinosissimus and Pararchaster 



semisquamatus) occur in depths less than 1000 fathoms. 



Greatest range of one species : Pararchaster semisquamatus, 565 to 1875 



fathoms. . 

 y. Nature of the Sea-bottom: Three species, viz., Pararchaster semisquamatus, 



Pararchaster antarcticus, and Pararchaster armatus, on Blue mud ; and 



Pararchaster semisquamatus is also found on the Green mud in 565 fathoms. 



Pararchaster pedicifer on Diatom ooze and Globigerina ooze ; and Pararchaster 



spinosissimus on Volcanic sand in 425 fathoms. 



i Bull. Mus. Comp. Zool, 1881, vol. ix. p. 28; Nouv. Archives Mus. Hist. Nat., 1884, 2e S6i., t. vi. p. 264. 

 2 hoc. cit. pi. i. fig. 8. 



