218 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



zooids grow older the cells composing them become scattered and in 

 some instances disappear. 



Nervous system (figs. 2, pi. 16, and 5, pi. 17). The ganglion is 

 rather prominent. The distribution of the nerves connected with 

 it is characteristic of the subgenus, as above described. The duct 

 of the subneural gland bends downward strongly before opening into 

 the pharynx (fig. 4 A, p. 206). 



Digestive tract. The esophagus, a short funnel-shaped tube, 

 enters the stomach posteriorly near its middle (figs. 3, pi. 16, and 4, pi. 

 17). In consequence of this peculiar juncture, the stomach has a 

 cloven or bilobate appearance. The intestine i3 rather wide and forms 

 an evenly curved loop, the oval anal opening lying opposite to the 

 dorsal end of the stomach on the left side. The digestive gland is 

 by no means conspicuous in this or in the following species (P. 

 spinosum). Over the gut it presents a few small ridges, which con- 

 verge to form the common duct of the gland. 



As before mentioned, the cloaca is very broad and short. Its 

 aperture is rather broad also, circular in outline, or broadly heart- 

 shaped (fig. 4, pi. 17). There is a tentacle on its dorsal edge in large 

 zooids ; in the immature zooids this is represented by a small thick- 

 ened prominence, or papilla, which shows the origin of the tentacle 

 (see figs. 3, pi. 16, and 7, pi. 18). This tentacle is flat and triangular, 

 and tapers to a narrow point when fully grown; its maximum length 

 about equals the widtJi of the atriopore. 



Gonads have not previously been observed in P. agassizi. In the 

 zooids of one of our colonies we find what we take to be the developing 

 testis (fig. 4, pi. 17). It lies between the two limbs of the digestive 

 tract, and consists of a number of indistinctly demarcated groups of 

 cells, which give a vague appearance of radiating from the central 

 mass. No duct could be discovered leading away from it. The egg 

 was not found, hence we are led to believe that some of the zooids, 

 at least, are protandrous. 



Occurrence and distribution. P. agassizi is known to occur in the 

 southern Atlantic, Indian, and Pacific Oceans. It seems to be most 

 abundant in the Pacific. 



Specimens of Pyrosoma agassizi were obtained at the following 

 dredging stations during the Albatross Philippine Expedition, 1907- 

 1910: 



D. 5126, Nogas Islands, Sulu Sea, vicinity of southern Panay; Feb. 

 3, 1908; 742 fathoms; surface temperature 80° F.; one spe-eimen, 

 Cat. No. 6488, U.S.N.M. 



D. 5233, Limasaua Island, between Bohol and Leyte; May 7, 

 1908; 15 fathoms; surface temperature 84° F.; surface density 

 1.02531; one specimen. Cat. No. 6422 U.S.N.M. 



D. 5320, China Sea, vicinity of Formosa; Nov. 5, 1908; 1,804 

 fathoms; surface temperature 80° F.; one specimen. Cat. No. 6423 

 U.S.N.M. 



