28 CLAVELINID^. 



C. lepadiformis, but having* wliite thoracic Hues : as the 

 latter, on our own coast, has these Hnes very frequently so 

 pale as to be nearly white, this may be only a variety. 

 The figure usually quoted from Miiller, of the original 

 lepadi/ormis, does not so closely represent the common 

 appearance of British specimens as that given imder the 

 name of Ascidia gelafinosa, in the fourth part of the "Zoolo- 

 gia Danica," edited by Rathke. 



PEROPIIORA, WiEGMANN. 



Individuals pedunculated, suborbicular, compressed, attached 

 by their pedicles to creeping tubular processes of the common 

 tunic, through which the blood circulates, Thorax not lincated 

 by granular bands. 



P. LisTERi, Wiegmann. 



J. Lister, on the Structure and Functions of tubular and cellular Polypi and of 

 Ascidise, Philosophical Transactions, 1834. [The author gave no name to his 

 Ascidian. When his paper was translated into the German journals, Professor 

 Wiegmann proposed the appellations here adopted.] 



Plate E, fig. 2. 



AVe have already noticed the characters of this curious 

 little animal or group of animals, so well described by Mr. 

 Lister. His account of the structure and economy of 

 Perojihora may be studied with advantage for its minute 

 accuracy. It threw light on the true nature of Clavelina, 

 which had previously been referred to the Simple Ascidians. 

 The Perophora Listen is a minute creature. It occurs not 

 rarely on the south coast of England, and we have taken 

 it in the Irish Sea. Mr. M 'Andrew and Professor E. 

 Forbes dredged it adhering to weed on the coast of An- 

 glesey in 1843. It is beautifully transparent, appearing in 

 the weed like little specks of jelly dotted with orange and 

 brown, and linked by a winding silvery thread. When 

 dried, as it may often be met with on sea-weed cast on 

 shore, these bodies appear like the minute ova of some 

 mollusk. 



