460 ON APPENDICULARIA FLABELLUM 



tentacles of the Polyzoa, which are entirely pre-pharyngeal 

 structures. 



Whatever may be the result of future inquiries as to the arrange- 

 ment of the female organs in Appendicularia, I cannot doubt that in 

 A. flabelluni we have an adult form in a male state. Whether the 

 female has a totally distinct form, or whether the ova are developed 

 in the same form at a subsequent period (I have observed individuals 

 so young that it is hardly conceivable that the ova should be de- 

 veloped at an earlier period), is a problem of very great interest, but 

 for whose solution I see no materials at present. Considering the 

 abundance in which Appendicularia occurs on our own shores, the 

 collection of the requisite data ought to present no great difficulties 

 to those who possess leisure and the opportunities of a sea-side 

 residence ; and to any such person, whose eye may fall upon these 

 pages, I commend the investigation as one A^-hich will amply reward 

 him. 



EXPLANATION OF PLATE X. [XXVIIL] 



Fig. I. Appendictilaria fiagelluin, seen from the side to which the caudal appendage is 



attached, i.e., the dorsalor heemal side. 

 Fig. 2. Body of Appendicularia, magnified, side view. 

 Fig. 3. Body of Appendictilaria, magnified, dorsal view. 

 Fig. 4. Caudal appendage ; showing the great nerve, with its ganglionic enlargements. 



A. Body. B. Appendage. 



a. Oral aperture. 



b. Pharynx, giving off its lateral canals, 

 f External opening of these canals. 



d. Ciliated circular bands, corresponding with the stigmata of the branchial sac in 

 ordinary Ascidians ; but here forming part of the wall of the canal b, c. 



e. Anus. 



f. Rectum. 



g. CEsophageal narrowing of the pharynx. 

 h. Right lobe of stomach. 



i. Left lobe. 



I;. Testis. 



/. Axis of caudal appendage. 



m. Rounded granular masses projecting from the hcemal wall of the pharynx, and 

 of doubtful natuie. 



n. Endostylc ; here, as elsewhere in Ascidians, the optical expression of the 

 thickened bottom of a groove or fold, continuous at its edges with the epipharyngeal 

 bands. 



0. One end of the heart. 



f. Ganglion. 



(J. Ciliated sac. 



?. Stolithic sac. 



J. Nerve trunk. 



t. Ganglionic enlargements upon its caudal portion. 



