78 PORCELLANASTERIDAE. 



sometimes two minute conical spinelets near the center of the margin, instead 

 of 2-5 large, flat spines occupying practically the entire margin. While the 

 abactinal surface of vicinus is thus indistinguishable, by any constant character, 

 from that of pacificus, the oral surface is separable at a glance. 



Station 4670. Peru: west of Palominos Light House, 105 miles, 3,209 fms. Bott. temp. 35.4°. Fne. 



dk. br. m. 

 Station 4672. Peru: southwest of Palominos Light House, 88 miles, 2,845 fms. Bott. temp. 35.2°. 



Fne. dk. br. infus. m. 



Forty-six specimens. 



Ctenodiscus crispatiis. 



Asterias crispata Retzius, 1805. Diss. Ast., p. 17. 



Ctenodiscus crispatus Duben and Koren, 1846. K. Vet. Akad. Handl. f. 1844, p. 256. 



So fully has this weU-known species been discussed by earlier writers and 

 particularly by Fisher (1911, Bull. 76 U. S. N. M., p. 31-37), it would be quite 

 superfluous to give space to its diversities here. The series at hand is a large 

 one but from only a single station, and the specimens range in diameter from 15 to 

 70 mm. 



Station 4631. Panama: off Mariato Point, 72 miies, 774 fms. Bott. temp. 38°. Gn. s. 



Thoracaster magnus. 



Plate 1, fig. 1, 2. 

 LuDWiQ, 1907. Zool. Anz. 31, p. 313. 



This truly superb species has been sufficiently described by Ludwig, who 

 has also pointed out some of the characteristic differences between it and the 

 genotype, which was taken by the Challenger in the Atlantic in 2,400 fms. 

 Since Ludwig described magnus, Koehler has pubUshed an account of a third 

 species of the genus, alberti, taken by the Investigator in the Indian Ocean in 

 1,504 fms. But alberti is obviously different in many particulars from either 

 of the other species, so that the genus contains three very well-marked forms. 



The cribriform organs of magnus tend to merge together to a very marked 

 degree, and apparently this is a matter of age. For in a specimen with R = 

 23 mm., these organs are quite distinct and although the three middle pairs 

 are very broad, much wider than the interspaces which separate them, they do 

 not merge at all; the outer pair are so narrow and inconspicuous, one would 

 scarcely consider them cribriform organs. On the other hand in a specimen 

 with R = 73 nun., all fourteen of the organs are more or less merged together; 

 those near the interradius are merged for practically their full height, being 



