HYALINOTHRIX, A NEW GENUS OF STARFISHES FROM 



THE HAWAIIAN ISLANDS. 



By Walter K. Fisher, 



Of Stanford University, California. 



The type of the new genus and species herein described was col- 

 lected in 1902 by the U. S. Fisheries steamer Albatross, near the island 

 of Molokai, Hawaiian Islands. The two specimens were received after 

 the publication of my report on the starfishes of the Hawaiian Islands. 



Hyalinoihrix superficially resembles two genera, which are not com- 

 monly considered closely related, namely Clisetaster and Nepantliia. 

 The resemblance to Clisetaster is chiefly in the character of the spine- 

 lets, in the tabulate abactinal plates, and in the form and armature 

 of the adambulacral and mouth plates. The most important difi'er- 

 ences between the two genera are listed below in parallel columns. 



Hyalinothrix. 



Abactinal plates with four or five lobes 

 which overlap those of neighboring plates; 

 no internal independent connecting 

 ossicles. 



Abactinal platea in quincunx only on 

 dorsolateral region of ray, and there in 

 more evident oblique and straight trans- 

 verse than in direct longitudinal series; 

 median radial plates more or less irregular; 

 abactinal plates in about forty longitudi- 

 nal series. 



Spinelets conspicuously longer than 

 height of tabulum, extremely delicate 

 and glassy. 



Marginal plates very small; an odd in- 

 terradial marginal probably absent. 



Superambulacral plates absent. Am- 

 pullae of tube feet incipiently two-lobed, 

 wider than high. 



Disk moderately small; rays tapering 

 from swollen base. 



Chxtaster. 



Abactinal plates with six very short 

 lobes which do not appreciably overlap 

 those of neighboring plates; four internal 

 independent ossicles present, binding to- 

 gether the plates of adjacent longitudinal 

 series. 



Abactinal plates arranged in quincunx 

 in nine very regular longitudinal series, 

 the median radial plates the largest. 



I 



Spinelets not longer than height of 

 tabulum and only moderately delicate. 



Marginal plates conspicuous; an odd 

 interradial marginal present. 



Superambulacral plates present. Am- 

 pullae of tube feet single, higher than 

 wide. 



Disk very small; rays very slender and 

 finger like. 



Proceedings U. S. National Museum, Vol. 39— No. 1807. 



659 



