246 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



One hybrid (?) and another specimen of doubtful subspecific rank 

 were taken in the Philippines, as follows: 



PYROSOMA ATLANTICUM ATLANTICUM X P. ATLANTICUM DIPLEUROSOMA. 



Cat. No. 6471, U.S.N.M., (Type) Albatross station D. 5223, Mala- 

 brigo Light, between Marinduque and Luzon, April 24, 1908; surface; 

 surface temperature 84° F. ; one specimen. 



PYROSOMA ATLANTICUM, subspecies. 



Cat. No. 6625, U.S.N.M., Albatross station D. 5124, east coast of 

 Mindoro, Philippine Islands; Feb. 2, 1908; surface; surface tem- 

 perature, 79° F.; surface density, 1.02468; one specimen. 



PYROSOMA ATLANTICUM HAWAIIENSE, new subspecies. 



Plate 28, fig. 34; plate 35, fig. 49. 



This is a form occurring in the northern Pacific Ocean, which, 

 according to our present knowledge, is truly distinct. All of the 

 specimens (six) were collected at one "catch," from a depth of five 

 fathoms, at a station between the Hawaiian Islands and California. 

 The characters by which this form is known make it so unique that 

 it might well be considered a new species, but its relation to the 

 species atlanticum is so evident that it seems well to class it as a 

 subspecies of atlanticum. In dealing with these spinous forms the 

 safer course has seemed to be to treat them all as nearly related, 

 although perhaps distinct, subspecies, because of the manifest ten- 

 dency on the part of some to intergrade with others. 



The colony is long and quite cylindrical, tapering scarcely at all 

 toward the closed end; some specimens are a little fusiform. The 

 cormus is relatively more slender than in specimens of P. atlanticum. 

 For example, the dimensions of the six specimens studied are as 

 follows: length of first 11 cm., width (average) 1.7 cm.; second, 

 length 12 cm., width 1.4 cm. (1.6 cm. at open end, 1.2 cm. at closed 

 end); third, length 16 cm., width 2 cm.; fourth, length 16 cm., 

 width 2.2 cm.; fifth, length 16 cm., width 2.4 cm.; sixth, length 17 

 cm., width 2.4 cm. From these figures it will be seen that there is 

 remarkable uniformity in the size and the form of the colonies, with 

 only slight differences in the relative width of each. 



The test processes are low, rounded protuberances with extremely 

 blunt ends. Over the entire outer surface of the colony there are 

 minute rounded elevations, which are visible only under magnifica- 

 tion, these giving to the test a granular opaqueness. It is worth 

 remarking here that the test processes of the largest colonies are all 

 proportionately more reduced in height and broader than those of 

 the smaller colonies, a condition which would suggest that the ances- 

 tral form from which this variety was derived had longer and more 

 pointed test processes. This is just what we should expect if the 



