158 BRITISH TUNICATA. 



tube therefore forms an open transverse loop, and that 

 which may be termed the rectal portion assumes a 

 regular sigmoidal curve. 



The liver is composed of numerous, large, oval 

 vesicles, scattered over the rectal portion of the intes- 

 tine. The minute twigs of the duct divide dicho- 

 tomously, and terminate in the vesicles, the points of 

 division being usually enlarged into ampullae. The 

 twigs unite and go to form a slender, short duct, 

 which passes from the intestine to the right side of 

 the stomach at the pyloric extremity, where the 

 hepatic fluid is mingled with the nutritive matters. 



The reproductive organs are situated within the 

 loop of the intestine, but their structure has not been 

 determined. The eggs, however, are apparently incu- 

 bated in the atrium at the sides of the branchial sac, 

 as we have seen the incipient tadpole larvae in this 

 position. 



1. Perophora Listeri [Forbes & Hanley].* 

 (Figs. 85 & 86.) 



Ascidia LISTER in Phil. Trans. 1834, p. 378, pi. xi; [FLEMING 

 Moll. Anim. (1837), p. 202, pi. xvii, f. 59]. 



Peroplwra WIEGMANN Archiv f. Xaturgescli. 1835 [I, p. 309] . 



Perophora Litteri FORBES & HANLEY Brit. Moll. I [1848], 

 p. 28, pi. E, ff. 2a, 2b ; [Cocxs in Rep. R. Cornw. Polyt. 

 Soc, 1849 (1850), p. 73; HUXLEY in Cams' Icon. Zootom. 



I (1851), pi. xviii, ff. 20, 21 ;] GOSSE Nat. Rambles Devon. 

 Coast [1853], p. 241, pi. xv, if. 1, 2; [HOEVEN Handb. 

 Zool. II (1856), p. 706; WOODWARD Man. Moll. (1856), 

 p. 340, pi. xxvii, f. 7 ; H. & A. ADAMS Gen. Recent Moll. 



II (1858), pi. cxxxiii, f. 8; OWEN in Encycl. Brit, ed. 8, 

 XV (1858), p. 332, f. 15 on p. 321 ; BRONN Thier-Reichs, 

 III, 1 (1861), pi. xvi, ff. 8-15]. 



* Forbes & Hanley (loc. cit. infra} and subsequent writers refer this 

 species to Wiegniann, but in his notice of Dr. Lister's paper he only gave the 

 name Perophora to the genus. The authors of this monograph leave the 

 authority for the specific name blank here, but give it as Wiegniann in 

 their synonymy, apparently having suspected that he was not the author 

 of it. 



