ASTEROIDEA 175 



Type locality. St. 175, Bransfield Strait, South Shetlands, 63° 17' 20" S, 

 59° 48' 15" W, 200 m., mud, stones, gravel. The type and a specimen with R 7-5 mm. 

 Taken also at St. 1948, north-east of Clarence Island, 60° 49-4' S, 52° 40' W, 490- 

 610 m., I specimen. 



Distribution. Known only from South Shetland Islands. 



Remarks. The specimen having R 7-5 mm. has the arched abactinal surface and neat 

 appearance of the type, but the actinal interradial areas are very small. Only the first 

 adambulacral plate has 5 furrow spinelets ; subambulacrals proximally 4. The number of 

 abactinal spinelets is of course variable but is of the order of 15 on the larger plates. 



The specimen from St. 1948, received long after the original collection, has R 19 mm., 

 r 8 mm., br 9 mm., and shows no important variations. 



L. densus is very different from any described species. As stated in the diagnosis its 

 dorsal aspect is that of a Leptychaster, while the close-set marginals on the actinolateral 

 border are so different from those of L. stellans that one may say the divergence in 

 general habit is as great as that between Solaster endeca and Crossaster papposiis. 



The type was dredged at the same station with Myoraster antarcticus. Of course this 

 species is distinguished at once by its generic peculiarity, the actinolateral muscle. But 

 superficially the paxillae are rather similar, though the spinelets differ in form. The 

 inferomarginals of Myoraster are much more prominent than those of densiis and the 

 actinal interradial areas are distinctly smaller. 



Genus Paralophaster nov. 



Diagnosis. Five-rayed Solasteridae closely similar to Lophaster, but without differ- 

 entiated superomarginal paxillae. Type Solaster godefroyi Koehler. 



Remarks. Koehler described 4 species of Antarctic Solasteridae having five rays but 

 differing from Lophaster in lacking differentiated superomarginal paxillae. These 

 species are: Solaster lorioli^ from 2500 fathoms, 67° 33' S, 36° 35' W; S . godefroyp irom 

 250 to 400 m., southern Bellingshausen Sea and off Queen Mary Land; S. incertus,^ 

 Kerguelen, shallow water; S. asperatus,'^ no fathoms, off Queen Mary Land. 



Since Koehler's Solaster included also Crossaster, it is probable that he had the latter 

 type in mind. In Crossaster the paxillae are penicillate and spaced ; the superomarginal 

 are subequal to the abactinal, while the inferomarginal are abruptly much larger. In 

 Solaster (e.g. S. endeca) there are definite, differentiated superomarginal paxillae, 

 although they are much smaller than the inferomarginals. 



Paralophaster has the appearance of a 5 -rayed Crossaster, but it lacks the membranous 

 interbrachial septum of Crossaster (absent also in Lophaster and Solaster). The abactinal 

 paxillae are arranged in oblique transverse rows as in Solaster, Lophaster, Myoraster, 

 but not as in Crossaster. 



1 Koehler, 1908, p. 558, pi. 4, figs. 40, 41. 



2 Koehler, 1912, p. 50, pi. 4, figs. 2, 6, 9, 10, 11; 1920, p. 153, pi. 31, fig. i; pi. 35, figs. 1-4; pi. 66, 

 fig. 9. 



3 Koehler, 1917, p. 40, pi. 5, figs. 2, 3; pi. 9, figs. 21, 22. 



4 Koehler, 1920, p. 157, pi. 33, figs. 8, 9; pi. 65, fig. 3. 



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