REPORT ON THE ASTEROIDEA. 279 



acquainted, and is readily distinguished from all the Pacific forms at present known. Its 

 o-eneral character poiuts to some alliance with Pentagonaster intermedins, of Avhich Penta- 

 gonaster arcuatus is perhaps the Pacific representative. In some of its structural details 

 Pentagonaster arcuatus resembles forms grouped in the genus Nymphaster, of which \ 

 was at first disposed to consider it an aberrant species. I am still in some doubt as to 

 whether this form is correctly referred to the genus Pentagonaster, but with only a single 

 example for study, that course appeared to me the most justifiable. 



Genus Calliaster, Gray. 



Calliaster, Gray, Ann. and Mag. Nat. Hist., 1840, vol. vi. p. 280. 



This genus was established by Gray in 1840, but was merged by Perrier 1 in 1876 in 

 the genus Pentagonaster, with doubtful subgeneric rank. A fine series of well-preserved 

 specimens, comprising the types of Gray's species, exist in the British Museum ; and after 

 a careful study of these, together with the new form, I consider that the genus established 

 by Gray should be maintained. The characters of the adambulacral armature, of the 

 actinal intermediate plates, aud of the general facies of the form appear to me to be 

 worthy of recognition, at least untd more is known of the internal anatomy of the various 

 members of the Pentagonasteridse, and of the true taxonomic value of the correlated 

 external structures. 



Chorology of the Genus Calliaster. 



a. Geographical distribution : — 



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

 Calliaster baccatus off the Cape of Good Hope. 



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

 Calliaster childreni off the coast of Japan. 



/3. Bathymetrical range: Appears to be confined to the Littoral zone : 18 fathoms is 

 the greatest depth recorded by the Challenger. 



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



Chorological Synopsis of the Species. 



1 Rcvis. StelL Mus., p. 215 (Archives dc ZqoI. exper., 1876, t. v. p. 31). 



