144 BRITISH TITNICATA. 



form elongated ampullae, particularly at the points of 

 division, and they terminate in round or ovate vesicles, 

 which are very numerous, and form a distinct, opaque, 

 yellow layer next to the surface of the intestine and 

 stomach. The ducts and twigs are more superficial. 



The reproductive system (PL XLVII, figs. 1-3, 6, 

 and 7) exhibits a bilateral symmetry, as is the case 

 with many of the GyntJiiadse. The ovaries are in 

 Pdonaia corrugata divided into two portions which 

 are attached respectively to the right and left sides of 

 the pallial chamber, having the branchial sac between 

 them, and the chief portion of the digestive organs 

 behind. They lie between the mantle and the lining 

 membrane, projecting in bold relief from the surface. 

 Each is composed of both male and female parts ; the 

 latter, being much elongated and tubular, are bent, 

 forming two wide loops that are turned downwards, 

 the forks or limbs of which are of unequal length and 

 directed upwards. The shorter limbs, which lie right 

 and left of the endostyle, terminate in blind sacs ; the 

 longer limbs extend upwards, and, having the rectal 

 portion of the intestine between them, terminate, far 

 in advance of the anus, in short, slender oviducts, one 

 on each side of, but considerably above, the anus ; the 

 extremities of the oviducts become free, and, projecting 

 from the pallial wall, open into the cloaca. 



The two lengthened ovigerous organs are fringed 

 on either side with numerous, elongated, simple, or 

 lobed vesicles composing the testis (PI. XLVII, figs. 6 

 and 7), which are placed with one end in contact with 

 the sides of the ovaries, and are arranged in parallel 

 order at right angles to them. From the proximal 

 extremities of the vesicles extremelv delicate ducts 



c/ 



pass across the surface of the ovary to which they are 

 attached, and go, frequently united in pairs, to join 

 the vas deferens, which extends along the middle line 

 from end to end of each ovigerous organ, and, advanc- 

 ing along the oviduct, terminates at the extremity of 

 that tube. 



