220 BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



the proportions of the colony cannot be determined. The colonies 

 appear to be cylindrical for the most part, and to taper but slightly 

 toward the closed end; more than this we can not assert. The test 

 is soft, gelatinous and extremely flabby. It is colorless in our speci- 

 mens. On its outer surface there are numerous quadrangular, or 

 triangular, spines such as we described for P. agassizi, each one placed 

 ventral to, and overarching the oral aperture of a zooid,(pl. 19). Or- 

 gans corresponding to the four elongated " tentacles" surrounding 

 the colonial aperture in P. agassizi, have not with certainty been 

 found in this species. Kruger (1912) has described as P. agassizi 

 an Atlantic Pyrosoma which apparently is no other than P. spino- 

 sum. As described and figured we would have no hesitation in as- 

 signing it to the latter species, for it has the characteristic form of 

 zooid, somewhat immature, and the complex musculature, numerous 

 stigmata, etc., peculiar to this species. But some of the colonies are 

 described as possessing four processes of the test, surrounding the 

 colonial aperture. We are uncertain whether this remark is meant 

 to apply to Kriiger's specimens, or to P. agassizi in general, according 

 to previous descriptions. If the former is the case, it would indicate 

 that some colonies of P. spinosum do bear these four processes. 

 Since they have been found to be so irregular in occurrence in P. 

 agassizi, it seems likely that they may be so in P. spinosum; that is, 

 present in some cases, absent in others, or perhaps large in young 

 colonies and sometimes absorbed in older ones. Farran (1906) re- 

 ports P. spinosum from the North Atlantic Ocean, figuring the colony 

 with four test processes around the colonial aperture, but no ade- 

 quate description of the zooids is given. There is no colonial dia- 

 phragm. The size of the colony is in a way rather distinctive; that 

 is, the largest colonies of Pyrosoma reported belong to this species. 

 Bonnier and Perez (1902) found specimens in the Indian ocean of 

 enormous size, the largest 4 m. long; others 2\ m. long, 20-30 cm. 

 in diameter. The majority of the specimens collected, however, do 

 not exceed 50 cm. in length. 



Zooids. An irregular arrangement of the zooids in the test obtains 

 in the younger colonies of P. spinosum. Large specimens have been 

 found in which there is a fairly regular arrangement of the zooids in 

 longitudinal rows, those in one row occupying alternate positions to 

 those in the adjacent rows (Hcrdman, 1888). Rather characteristic 

 of this species is the thickness of the test wall, and coordinated with 

 this, the extraordinary length of the zooids. Mature individuals, 

 from medium-sized colonies, measure 0.8 cm. — 1 cm. in length from the 

 mouth to the base of the cloacal tentacle. The largest ones known 

 are fully 2 cm. long (see Neumann, 1909-13). They are about 3 mm. 

 to 4 mm. in width. We find in our specimens that the ventral side of 

 the zooid is directed toward the closed end of the colony, as we might 



