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, 3,209fms. 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 crispatus. 
Asterias crispata Retztus, 1805. Diss. Ast., p. 17. 
Ctenodiscus crispatus Di@BEN AND Koren, 1846. K. Vet. Akad. Handl. f. 1844, p. 256. 
So fully has this well-known species been discussed by earlier writers and 
particularly by Fisher (1911, Bull. 76 U. 8. 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 miles, 774 fms. Bott. temp. 38°. Gn. s. 
Thoracaster magnus. 
Plate 1, fig. 1, 2. 
Lupwie, 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 published an account of a third 
species of the genus, alberti, taken by the Investicaror 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 mm., all fourteen of the organs are more or less merged together; 
those near the interradius are merged for practically their full height, being 
