NUDIBRANCHIATA OF THE L.M.B.C. DISTRICT. 139 



narrows gradually at its lower end and passes over into 

 the connecLing tube which is bent upon itself in a sigmoid 

 curve. Fig. 6 shows a section in which hepatic caecum (/i.e.), 

 connecting tube (cd.) and cnidophorous sac (c.s.) occur 

 together all cut transversely. The large cells or cnidocysts 

 in which the thread-cells lie (fig. 6, c.s.) are distinctly 

 nucleated and contain each a very large number of cnida. 

 They get much smaller at the upper and lower ends of the 

 sac and pass gradually into the ordinary ectoderm cells on 

 the one hand and the cubical or low columnar cells of the 

 connecting duct on the other. 



The cnida are of elongated fusiform shape and are 

 slightly curved * (fig. 7) . None were seen in the exploded 

 state. At the junction of the connecting tube with the 

 apex of the hepatic caecum the cubical epithelium passes 

 gradually into the glandular hepatic, cells, and there appears 

 to be no distinct sphincter present. Figure 5 shows the 

 very narrow opening of the hepatic caecum into the lateral 

 branch of the liver (/./.) leading to the posterior end of 

 the stomach. 

 Facelina {Acanthopsole) drummondi, Thompson. 



A number of specimens were found at Hilbre Island 

 on September 9th, 1889, at extreme low water. 



The remarkably long curved connecting duct between 

 the cnidophorous sac and the hepatic caecum in this species 

 is shown in PI. IX. fig. 8, cd. PL IX. fig. 9 shows the 



* These are evidently the forms described by Vayssiere as the reniform 

 nematocysts (Ann. du Miis. d'Hist. Nat. de Marseille, Zool. t. iii., Mem. 4, 

 p. 40, 1888) ; we have not found the second kind described as oviform. 

 Bergh, in his recently published admirable account of the Cladohepatic 

 Nudibranchs (Zoolog. Jahrblich., Bd. v. 1890), seems to consider it still 

 doubtful whether more than the one kind of cnida is really produced in the 

 cnidophorous sac, but Vayssiere's figures show very distinctly, in the case of 

 Coryphella landshurgi at least, unbroken cnidocysts containing two distinct 

 kinds of cnida, large reniform and small pyriform. 



