384 POLYZOA INFUNDIBULATA. 



tinned below tlie edge of the tunic, and the current produced in the 

 water, and the food it brought, flowed into a cavity there, at the 

 bottom of which was active indistinct motion as if of filaments. A 

 connexion was thought to exist between that part and the place 

 where the revolution was going on, but no act of deglutition was 

 perceived. 



" No current of blood was visible in the stem, nor any circulation 

 either in the body or the arms. Much of the space within the tu- 

 nic was occupied by a darkish appearance, the nature of which was 

 not ascertained. I had not opportunity to inspect other individu- 

 als, but the species seemed to be intermediate between such animals 

 of Flustra as I had met with, and the pedunculated compound 

 Ascidia; more nearly related to the former, but approaching the 

 latter in the form of the lower part of the body, the position of the 

 rectum, and the absence of all apparent effort of swallowing : and if 

 with the help of imagination we could connect the ciliated arms to- 

 gether by cross bands at intervals and unite their ends in a circle, 

 extending the tunic to meet that circle, and leaving an opening for 

 the funnel where the rectum is placed, the organ would not be unlike 

 the branchife of some Ascidise. Indeed the affinity appeared to me 

 not very distant between Ascidia and Flustra; while, to the Sertu- 

 larire, except in the resemblance given by their projecting arms, I 

 can discover no more analogy in the FlustrjB than in the Ascidife 

 themselves." — Lister. 



The pedicles are often so infested with microscopic parasitical 

 Diatomaceae that their spinous character is obscured or rendered un- 

 certain ; and I think it not improbable that Mr. Lister and Professor 

 Sharpey were thus induced to represent the stalks without any 

 spines. " In some specimens," says Professor J. Reid, " the stalk is 

 nearly smooth, in others several spinous-looking processes project 

 from it, and in others both stalk and body are covered with a long, 

 fine, and sparse down." 



Pedicellina echinata is, according to Professor Reid, more hardy 

 than most of the other ascidian polypes, and can be kept alive at 

 home for a long time. The number of tentacula varies from fourteen 

 to twenty. Like the hydroid Tubularinfe, the life of the body is of 

 shorter duration than that of the stalks, the former fading and falling 

 off, when a new one is reproduced in its place. "A few days before 

 this takes place, the tentacula are permanently bent inwards and the 

 membrane surrounding their lower part remains contracted, so as to 

 completely, or nearly completely, cover the upper surface of the body, 



