TRIPYLASTER PHILIPPII. 177 



Abatus koehleri. 



Hemiaster elongatus Kochlcr, 1907. Zool. Anz., 32, p. 147 (preoccupied). 



Hemiaster koehleri Thiery, 1909. Rev. Crit. Pal., 13, p. 137. 



Abatus elongatus Mortensen, 1910. Swedish South Polar Exp. Ech., p. 87. 



This species, which may perhaps be identical with agassizii, is based on 

 four specimens from Scotia Bay, South Orkneys. It is a little odd that not 

 only Mortensen (1910) but Koehler himself (1911) overlooked Thiery's cor- 

 rection of the name. 



Abatus nimrodi. 



Pseudabatus nimrodi Koehler, 1911. British Antarctic Exp. Biol., 2, pt. 4, p. 60. 



Although Koehler himself considers this form well enough marked to be 

 the type of a new genus, I must confess that until all the growth-stages of shackle- 

 toni are known, I shall be unable to accept such a conclusion. Indeed, the 

 pedicellariae seem to be the best reason for considering nimrodi a, different species 

 from shackletoni, which occurs at the same location. The only two known speci- 

 mens of nimrodi are from Cape Royd's Bay, Antarctica. 



Tripylaster. 



Mortensen, 1907. Ingolf Ech., pt. 2, p. 122. 

 Type, Tripylus philippii Gray, 1851. Ann. Mag. Nat. Hist., (2), 7, p. 132. 



As Mortensen has pointed out (1910. Swedish South Polar Exp. Ech., p. 69) 

 this genus seems to be intermediate between Abatus and Brisaster. Indeed 

 the difference from the latter is so slight, I hesitate to accept the genus. But 

 for the present, there seems no better course. 



Tripylaster philippii. 



Tripylus philippii Gray, 1851. Ann. Mag. Nat. Hist., (2), 7, p. 132. 

 Schizaster (Tripylaster) philippii Mortensen, 1907. Ingolf Ech., pt. 2, p. 122. 



Plate 155, figs. 7, 9. 



As this species has been long known from both sides of Patagonia, and 

 has been studied and described by a number of writers, there is nothing to add. 

 But two photographs of an unusually perfect bare test are given for the 



