ANATOMY AND DEVELOPMENT. 



189 



a duct which runs forward and opens at the end of a 



ciliated funnel-shaped dilatation into the branchial sac at 



the base of the buccal tube 



(Figs. 94, 96, and 97) in 



front of the peripharyngeal 



band. 



The branchial opening of 

 the duct of the subneural 

 gland appears primarily as 

 a simple circular orifice, but 

 it does not usually retain 

 this character in the adult. 



Generally it assumes a 

 crescentic form by the in- 

 curving of its anterior or 

 posterior lip, and then in 

 many cases the horns of the 

 crescent so formed become 

 coiled over and over con- 

 centrically, and usually in 



, u Fig. 96. Young Clavelina, shortly 



approximately the Same after the metamorphosis, from the right 



plane, so that the lips of side - (After VAN BENEDEN and JULIN.) 



at. Atrial opening, at.c. Atnal cav- 



the aperture assume a Very ity. b.s. Blood-sinus, end. Endostyle. 

 , . -. ep. Epicardium ; outgrowth from bran- 



complicated appearance and chial sac behind e ndost y ie, which grows 

 constitute the so-called dor- down into the cree P' n g stolon - formin s 



a septum in the latter, and being the 



Sal tubercle (Fig. 97). chief element in the production of buds. 



,, . . / Lobes of the fixing organ, which give 



It has taken a long time rise to the creep ing stolon, g. Ganglion. 



and the WOrk Of a great f-*- Stigmata. A. Heart, hy. Hypophysis 



. (dorsal tubercle), int. Intestine. m. 



many Zoologists tO achieve Mouth, oes. (Esophagus. p.b. Periphar- 



i T yneeal band. pc. Pericardium. /. Re- 



our present knowledge ma s ins of tai]> 4 hdrawn into the body. 



(which is by no means * Visceral nerve. 



complete) of the subneural gland of Ascidians and its 

 duct. 



