SEA-SQUIRTS. 



149 



Appendiculariae. These (Fig. 188) are the simplest 

 forms of the class, minute pelagic creatures with tadpole- 

 like tails. 



FIG. \$.Appendicularia flabellum. I. The entire animal, with the 

 *' tail " hi its ordinary position, or turned forward. II. Side view of the 

 body, with the "tail" forcibly bent backward. A, the body; B, the 

 iail ; a, oral aperture ; , the pharynx ; c, an atrial opening ; </, the cor- 

 responding stigma, with its cilia ; _/", rectum ; g , oesophagus ; Jt, /', stom- 

 ach ; /, urochord ; m, cellular patch at the side of the oral end of the 

 body ; p, ganglion ; 7, ciliated sac ; r, ear ; s, posterior nerve with its 

 ganglia, t ; en, endoderm ; ec, ectoderm. (After Huxley.) 



Works on Tunicates for further reference. 



" Ascidians of the Coast of New England," A. E. Verrill, in " Ameri- 

 can Journal of Science," vol. i, 1871 ; " Structure and Affinities of the 

 Sea-Squirts (Tunicata)," J. C. Gallon, " Popular Science Review," July, 

 1868 ; " Invertebrata of Vineyard Sound," Verrill ; " Development 

 of Salpa," Brooks, " Bulletin of Comparative Zoology," Cambridge, 

 1876. 



