118 



BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



or the ducts of the neural glands. The remarkable absence of these 

 organs in this species may be associated with the great rotation of 

 the ganglion. It is of interest as showing that these organs are 

 not of indispensable physiological importance in the Salps, for this 

 species, which lacks these organs, is the most abundant and widely 

 distributed of all the species in the family. 



THALIA DEMOCRATICA, aggregated zooid: Philippine form. 



Characteristic specimens of the Philippine form of aggregated 

 zooids of this species are in the collections of United States National 

 Museum as follows: 



Cat. Nos. 6473 (Holotype) and 6474 (Paratype) U. S. N. M. (Ag- 

 gregated, Philippine form), Albatross station D. 5456; June 7, 1909; 

 142 fathoms; surface temperature, 86° F. ; two specimens. 

 In the prevalent form of the aggregated zooids of Thalia 



democratica from the 

 Atlantic coast of the 

 United States (fig. 107, 

 A and B) there are but 

 few tubular protuber- 

 ances of the mantle 

 into the test. At one 

 of the postero -lateral 

 angles of the body there 

 is one which protrudes 

 slightly beyond the 

 general contour of the 

 test. There are gener- 

 ally an unequal pair in front not protruding beyond the general 

 contour of the test. If there are others the}' are generally weakly 

 developed. 



On the other hand, in the Philippine collections of this species, 

 made by the Bureau of Fisheries steamer Albatross, there are very 

 numerous specimens of a form of aggregated zooid, which show more 

 numerous and much more developed mantle protuberances (fig. 107, C). 

 This zooid strikingly resembles Traustedtia radiata in musculature, 

 form of "nucleus," and "tentacles." This resemblance is so marked 

 that one, at first glance, thinks these zooids to be the aggregated 

 form of the latter species. The testis in these aberrant Philippine 

 zooids is readily seen to be in the form of four lobes surrounding 

 the intestine. 



Among the Atlantic specimens are some which, in the number of 

 mantle protuberances, approach the Philippine type, but I have 

 found none with the protuberances so well developed as in the latter. 



Fiq. 112.— Thalia democratica, aggregated form, longitudinal 

 vertical section of ganglion and eyes, showing thf. inner- 

 vation of e',5. x 300 diameters. from metcalf (1893, c). 



