liowERBANKiA. Z. ASCIDIOIDA. 255 



*214. Flem. Brit. Anim. 551 — Vesiculaiia piistuloHa, Thump. Zool. 

 111. 99, pi. 1, fig. 5—11. 



Hab. Parasitical on Fuci. Isle of Wight, Ellis. Cove Harbour, 

 J. V. Thompson. 



This " arises from the surface of marine fuci with a straight flex- 

 uose stem, to the height of two or three inches, giving off at each 

 flexure a spreading branch, which in like manner gives off secondary 

 ones, all however, both primary and secondary, lying in the same 

 plane, they are hence what botanists term distich ; each flexure of 

 the stem and branches and each terminal branchlet is composed of a 

 distinct joint, each of which are perforated by a double row of holes 

 from 6 to 18 with elevated margins, on all of which in perfect speci- 

 mens are placed oval transparent vesicles, furnished with animals hav- 

 ing 8 tentacula : the rows of perforations having a spiral tendency, 

 the clusters of vesicles hence present themselves in every direction." 

 Thomjjson. 



25. BovvERBANKiA,* Farre. 

 Character. Polypidom confervoid, horny, creeping; the 

 cells sessile, unilateral, irregular, the inflected portion with a spi- 

 nous or filamentous rim : — Polypes ascidian. 



1. B. DENSA, matted ; stem creeping ; cells from the sides and 

 upper surjace, thiclily set, elliptical : Polypes ivith 10 tentacula 

 about one-third the length of the body, sparingly hispid along the 



outer side. Farre. 



Bowerbankia densa, Farre in Phil. Trans, an. 1837, 391, pi. 20 and 21. 

 Hab. " Found commonly on Flustra foliacea thickly aggregated in 

 masses of half of an inch to one inch diameter." Isle of Sheppey, 

 Parre. 



" The animal when fully expanded is about one-twelfth of an inch 

 in length. In its retracted state it is completely inclosed in a de- 

 licate horny cell, sufficiently transparent to admit of the whole struc- 

 ture of the contained animal being seen through its parietes. The 

 cells are connected together by a cylindrical creeping stem, upon 

 which they are thickly set, and sessile, ascending from its sides and 

 upper surface." 



* " Believing it to be new I have named it after my friend Mr Bowerbank, 

 whose zeal displayed on this as on many other occasions where the study of na- 

 tural history may be promoted, was mainly instrumental in inducing me to fol- 

 low up these investigations, on account of the many supplies that I received from 

 him, and I gladly therefore take the opportunity of acknowledging and record- 

 ing tlie obligation that I am under to him." Dr Farre. 



