108 



BULLETIN 100, UNITED STATES NATIONAL MUSEUM. 



that of most other Salpidae, Thalia democratica showing the most 



similar condition. 



an. 



k , /, 



Fig. 101.— Tasis zonaria, aggregated zooid, longitudinal vertical sections of the ganglion, 

 eye, and ciliated funnel. x 97 diameters. from metcalf (1893, c). 



The gut (fig. 97) is a compact "nucleus," in which, however, the 

 course of the intestine is readily seen without dissection. 



The large dorsal eye 

 (figs. 101 and 102) is 

 very compact, the typi- 

 cally distal portion being 

 drawn back beneath the 

 true basal portion, mak- 

 ing the whole eye nearly 

 spherical. The thick- 

 walled ends of the rod- 

 colls are somewhat irreg- 

 ular, but the cells can 

 hardly be called degen- 

 erate. 



There are no acces- 

 sory eyes in the gan- 

 glion of this species, but on each side of the ganglion there is a huge 

 outgrowth (fig. 103 ey) composed 

 of irregular cells with unevenly 

 thickened walls, like degenerate 

 rod-cells, as for instance, in the 

 accessory eye of the aggregated 

 Salpa fusiformis (fig. 79, p. 92). 

 These outgrowths resemble those 

 of the solitary Iasis. They are 

 sessile upon tho ganglion. They 

 lie above the lateral pouches of 

 the neural gland, in a position cor- 

 responding to that of the largo-celled outgrowths from the ganglion in 

 other species, with which they arc probably homologous. 



Fig. 102.— Tasis zonaria, aggregated form, sagittal section 

 of the eye. x 476 diameters. from metcalf (1893, c). 



Fig. 103.— Iasis zonaria, aggregated form, 

 schematic ventral view of the ganglion, the 

 lateral outgrowths from the ganglion and 

 the neural gland. x 40 diameters. a re- 

 construction frou sections. 



