498 PROCEEDINGS OF THE NATIONAL MUSEUM vol. 8^5 



Genotype. — Aleutiaster Hchejfein^ new species. 



Habitat. — Aleutian Islands; 1-7 fathoms. 



Remarks. — At fii-st I regarded Aleutimter as most closely related 

 to Perknaster, later deciding that its affinities were rather with 

 Cycethra. I have never been able to examine a specimen of any 

 species of Perknmter^ which I knovr only from descriptions and 

 figures. 



Prof. Walter K. Fisher, who examined the two specimens of Aleut'- 

 aster scheffen, writes that he is of the opinion that AJeutimter is a 

 little nearer to Perknaster than to Cycethra — or possibly the three 

 genera may be placed at the three apices of a triangle. 



Both the specimens of the type species of Aleutiaster are very small 

 and possibly innnature, but their characters are so distinctive that 

 even if the adults should prove to be much larger they will be readily 

 recognizable. 



ALBUTIASTER SCHEFFERI, new species 

 Plate 57, Figi^res 1-4 



Description. — A very small species with six short arms, perhaps 

 bettier described as hexagonal v.ith obtuse reentrant angles. The 

 abactinal surface is elevated, having a somewhat inflated appearance, 

 and the abactinal side passes over in a broad curve to the flat actin-il 

 surface. The entire animal is covered with a thick skin, which com- 

 pletely conceals the underlying plates. The spines are enclosed in 

 skin sacks, and the adanibr.lacral spine combs are webbed. The re- 

 semblance at first glance to a small Pteraster is striking. Ii = 5 nun.; 

 r = 3.5 mm. R = about 1.4 r. Height at center, 3.5 mm. ( = r). 



The plates on the abactinal surface are very thin, scalelike, glassy, 

 and very strongly imbricating. Those in the center are circular to 

 broadly 4- or 5-lobed, or more or less elongate; those on the 

 arms are broadly and roundedly wedge-shaped. Each plate has an 

 abruptly thickened and roundedly elevated opaque portion that 

 stands high up from the glassy scalelike base. This elevated por- 

 tion is central on som.e of the plates on the disk, but on the plates on 

 the arms it involves the adcentral half, or rather less^ on these 

 plates it is somewhat elongate transvei'sely and commonly has a 

 slightly concave thickened adcentral border. Interradially as the 

 abactinal passes into the actinal surface the plates become elongate- 

 triangular with the swollen narrow base away from the mouth. In 

 the central portion of the abactinal surface the plates are somewhat 

 irregular in arrangement, but on the arms they become arranged in 

 diagonal lines. The greater portion of each plate is concealed be- 

 neath the plate following, so that the abactinal surface seems to be 

 covered by the thickened and elevated portions of the plates, slightly 



