10 BRITISH TUNICATA. 



Amoroucium albicaiis THOMPSON [in Rep. Brit. Assoc. for 



1852 (1853), p. 293, and] Nat. Hist. Ireland, IV [1856], 



p. 362. 

 \_Amaruoium ulbicans G-RUBE Insel Lus&in Meeresf. (1864), 



pp. 30, 57.] 

 \_AmaroBcium albicans NORMAN in Rep. Brit. Assoc. for 1868 



(1869), p. 303.] 



Colony variable, incrusting, massive, or sub-clavate 

 and pedunculate (PI. LIU, fig. 6), of a greyish-white 

 colour. Individuals numerous, arranged in elliptical 

 systems of various sizes, sometimes nearly circular, 

 but more frequently elongated (PI. LIU, fig. 5). 

 Thorax and branchial aperture white (PI. LVI, fig. 3), 

 the latter cut into six conspicuous segments; atrial 

 aperture with a longish process above. Stomach 

 orange-coloured, plicated. Post-abdomen paler, mode- 

 rately long and pointed below. 



Height and diameter of the masses variable, incrust- 

 ing specimens sometimes extending to two inches 

 (50 mm.) across. 



Rob. On rocks and stones between tide-marks 

 and at a depth of several fathoms. 



ENGLAND. Bambrough, Xorthumb. (Alder}. 

 IRELAND. [Belfast Bay, dredged (1839); and] off 

 the Galway Coast [J840]' '(Thompson). 



CHANNEL ISLANDS.- Guernsey [1805] (Norman).. 

 First record.- -Thompson, 1&48. 



All the British specimens we have seen have been 

 the incrusting or massive forms. They had minute 

 calcareous granules on the surface. 



3. Amaroucium papillosum Alder. 

 (Plate LIII, fig. 7.) 



Amarsecium papillosum ALDER in Ann. Nat. Hist. (3) XI 

 [1863], p. 171. 



Colony depressed, sessile, yellowish fawn-coloured. 

 Individuals prominent, rising into distinct papilla? over 

 the surface (PL LIU, fig. 7), and forming numerous 



