NOTE ON THE CILIATED PIT OF ASCIDIANS. 131 



Note on the Ciliated Pit of Ascidians and its 

 Relation to the Nerve-ganglion and so-called 

 Hypophysial Gland; and an Account of the 

 Anatomy of Cynthia rustica (?). 



By 



Lilian Sbelclon, 



Bathurst Student, Newnham College, Cambridge. 



With Plates IX and X. 



In the adult Ascidians which I have examined, I find tour 

 main variations of the ciliated pit. 



(1) In Clavellina the ciliated pit (fig. 1, C.P.) is simple 

 in shape, its opening into the mouth being round in section. 

 It lies ventral to the nerve-ganglion (N.G.), into the solid sub- 

 stance of which it leads by a wide opening (B.), situated near 

 the anterior end of the ganglion. Behind the opening it 

 narrows, and passes on into a canal (C), lying immediately 

 ventral to the ganglion. The cells lining this canal are flatter 

 than those at its orifice, and are not ciliated. A large number 

 of glandular tubes (Gl.) lie ventral to it and open into it. 

 Seeliger 1 states that the hypophysial gland never attains to 

 the complicated condition, which Julin 2 describes in some 

 simple Ascidians. I find, however, that the gland is large and 

 made up of branching tubes which open into the backward 



1 Seeliger, O, "Die Eutwicklungsgischichte de socialeu Ascidien," ' Je- 

 naische Zeitschrift fur Naturgewisseiischaft,' 1885. 



2 Julin, Charles, " llecherches sur l'organibation des Ascidies simples, sur 

 l'hypophyse et quelques organs qui s'y rattachent," 'Archives de Biologie,' 

 Tomeii, 1881. 



