170 HAWAIIAN AND OTHER PACIFIC ECHINI. 



Protenaster rostratus. 



Linthia rostrata Smith, 1878. Ann. Mag. Nat. Hist., (5), 1, p. 67. 



The unique holotype of this species is a bare test from an unknown locality, 

 supposed to be in the Pacific. 



Paraster. 



Type, Schizasler gibberulus Agassiz and Desor, 1847. Ann. Sci. Nat. Zool., (3), 8, p. 22. 



In his skilful handling of the genus Schizaster, Mortensen (1907. Ingolf, 

 Ech. pt. 2, p. 108-123) has laid all students of Echini under great obligation, but 

 the groups which he considers subgenera seem worthy of generic rank, and 

 even wider separation between Paraster and the others is desirable. In addition 

 to the two species which Mortensen places in this genus, I put Doderlein's 

 Linthia rotundata and Studer's Hemiaster florigerus here, and Koehler has added 

 a fifth species from Indian seas. I am very much in doubt whether savignyi 

 is a valid species but have not the necessary material to determine whether 

 it is really different from gibberulus. 



Key to the Species of Paraster. 



Lateroanal fasciole present. 



Actinal primary tubercles small, numerous and more or less crowded, there being 

 200 =*= on the sternum. 



Test high, v. d. posteriorly .70 length or more. 



Anterior end of test much lower than posterior: ambulacrum III deeply 



sunken at ambitus gibberulus. 



Anterior end of test about as high as posterior; ambulacrum III not 



deeply sunken rotundatus. 



Test lower, v. d. .65 length or less, sloping anteriorly from abactinal system but 



not so markedly as in gibberulus saiignyi. 



Retinal primary tubercles large and relatively few, 100 or fewer on sternum of test 

 19 min. long; tuberculated area of sternum about .75 as wide as long .... compactus. 

 No lateroanal fasciole florigerus. 



Paraster gibberulus. 



Schizaster gibberulus Agassiz and Desor, 1847. Ann. Sci. Nat. Zool., (3\ 8, p. 23. 

 Paraster gibberulus Pomel, 1869. Revue Ech., p. xiv 



Fourtau (1904, Bull. Inst. Egypt., (4), 4, p. 434^436) and Koehler (1914. 

 Ech. Indian Mus. Spat., p. 172-180) have thrown much light on this hitherto 



