236 



THE ASCIDIANS. 



ance, doubles up obliquely forwards to the left atrial 

 chamber, into which it opens by the anus (Fig. 107). 



In the angle made by the outgoing intestine with the 

 stomach, a blind diverticulum arises. It is at first a sim- 

 ple coecum, but soon begins to branch (Fig. 105 C), and 

 finally forms an arborescent growth embracing the in- 

 testine (Fig. 107). This is the so-called pyloric gland, 

 and it is probably homologous with the hepatic cceciim of 

 Amphioxus. 



Appendicidaria. 



It is generally agreed among those who have a voice in 

 the matter, that most of the pelagic Ascidians (Salpa, 



Doliolum, Pyrosoma) are 

 highly modified forms, spe- 

 cially adapted to a pelagic 

 life, one of the results of 

 which is that their repro- 

 duction is marked by a 

 complicated alternation of 

 generations. 



It would, therefore, not 

 assist us in our comparison 

 with Amphioxus to describe 

 these types. 



There is, however, one 

 family of pelagic Ascidians, 

 the Appciidicnlaricv, with re- 

 spect to which there are two 

 widely different opinions. 

 Fig. z-Li. — Appt:iidic:i!aria {Fritii- The Appendicularijc are 



laria) furcata, from the ventral surface. ... 



(After lankester.) pelagic, free-swimming As- 



u. Anus. f'/. Unicellular glands, e.s. ^;j;^„„ .,,u„ „ i I4- j- 



Gill-slits. /,. Dorsal hood-ifke fold of "dians, whosc adult condi- 

 integument. m. Mouth, t. Tail. tion is SO far similar to the 



