A TAXOXOMIC STUDY ON PYROSOMA METCALF AND HOPKINS. 257 



Distribution: P. atlanticum triangulum occurs in the Indian and 

 Pacific Oceans. In the Indian Ocean one specimen was taken by the 

 Valclwia in 1899 off the Somali coast (Deutsche Tiefsec Expedition 

 station 263). The following specimens were taken by the Albatross 

 during the Philippine Expedition of 1907-1910, and off Japan in 1910: 



D. 5402, Capitancillo Island Light, off Northern Cebu Island; 

 March 16, 1909; 188 fathoms; surface temperature, 81° F. ; one speci- 

 men; Cat. No. 6495, U.S.N.M. 



D. 5410, Bagacay Point Light, between Cebu and Leyte; March 

 18, 1909; 385 fathoms; surface temperature, 80° F.; one specimen; 

 Oat, No. 6415, U.S.N.M. 



An unnumbered station off Honshu, Japan, 1910, one specimen. 



PYROSOMA ATLANTICUM ECHINATUM, new subspecies. 



Plate 35, fig. 48; plate 31, fig. 38. 



A single, large Pyrosoma specimen in our possession, procured from 

 the Naples Zoological Station and labeled by them P. elegans, seems 

 to merit a separate treatment in this rather detailed study of the 

 entire group. It is possible that this is nothing more than a colony 

 of P. atlanticum giganteum; but, if so, it is the only specimen of thin 

 form which we have studied which is so perfectly transparent and 

 colorless, 1 and which bears such extremely long and numerous test 

 processes. It is probable, but not definitely known, that this speci- 

 men was taken from the Mediterranean Sea. Apparently this form 

 is identical with the Naples species referred to by Kruger (1912, 

 p. 6) as P. elegans, which he says is characterized by extremely long 

 oral siphons. There is no indication that this is the form to which 

 Lesueur originally gave the name elegans. To avoid confusion, it 

 seems best not to use this name. Kriiger's reference is insufficient 

 for certain identification of the form he had. 



The colony is a thick, cylindrical tube, and tapers but slightly 

 toward the closed end; its widest part is near the middle. The 

 dimensions are: length 12.5 cm., width at open end 2.8 cm., at 

 middle 3 cm., at closed end 2 cm. The test is transparent, the 

 whitish zooids giving to the whole colony a white appearance. Nearly 

 all the test processes are long and fingerlike, and bend in the direction 

 of the colonial aperture. At their ends they are not sharply pointed, 

 but are narrow, and in edge view for the most part emarginate, being 

 narrowed on the outward side. They average about 8 mm. in length, 

 the largest of them attaining 1.3 cm. 



Each of the more mature zooids has an extended oral-siphon, open- 

 ing onto a test-process, near its tip. These zooids arc narrow and 

 tube-like, reaching a length of 0.9 cm. -1.9 cm. The less mature 

 individuals average 0.6 cm. long; they appear slender and ovoid, 



1 Our specimen is preserved in alcohol. 

 7911—19 5 



