THYLACIUM VARIOLOSUM. 139 



wrinkled or nearly smooth, generally red towards the 

 anterior and paler towards the opposite end, with a 

 whitish raised circle around each aperture, that of the 

 branchial largest and radiated with red. Individuals 

 (PI. XL VI, figs. 12 and 13) connected by a mem- 

 branous expansion, at the base, of a paler colour. 

 Tentacular filaments linear, stout. 



Length (transverse) of individuals about one-eighth 

 of an inch. Diameter of the general mass one-half to 

 three-quarters of an inch. 



Hab. On Fucus palmatus [? = Rhodymenia palmata] 

 (Gaertner) ; on the test of Cynthia [Styela] mamillaris 

 (Jeffreys'):, on the carapace of Maia squinada (Norman}. 



ENGLAND. Lulworth Cove, Dorset (Jeffreys). [Coast 

 of Cornwall (Gaertner) .~\ 



CHANNEL ISLANDS. Guernsey (Norman). 



First record. Gaertner [1774]. 



Genus 10. PELONAIA* Forbes & Goodsir, 1841. 



Pelonaia FORBES & GOODSIR fin Eep. Brit. Assoc. for 1840 

 (1841), Sect, p. 137, and] in Ediiib. new Plrilos. Journ. 

 XXXI (1841), p. 29 ; FORBES & HANLEY Brit. Moll. I 

 [1848], p. 42; ALDER & HANCOCK in Trans. Tyneside Nat. 

 Field Club, I [1848], p. 195; H. & A. ADAMS Gen. Recent 

 Moll. II [1858], p. 593. 



[Ascidia (pars) DALYELL Rare Aiiim. Scotl. II (1848), p. 141.] 

 Pelontea WOODWARD Man. Moll. [1856], p. 338. 



Animal free or very slightly adhering by glandular 

 fibrils, elongated, cylindrical, vermiform, broadish and 

 rounded or obtusely pointed towards the inferior end. 

 Apertures 4-lobed, terminal, on short, conical papilla?. 

 Test tough, closely adhering to the mantle. Tentacular 

 filaments linear, small. Branchial sac without folds, 

 extending two-thirds down the body ; meshes recti- 

 linear. Stomach and intestine sub-abdominal. Repro- 

 ductive organs on both sides of the branchial or thoracic 

 portion of the body. 



* "Pelonaea" in the transcript of the authors' MS., throughout. 



