ASCIDIA SCABBA. 129 



transparent, yellowish white, more or less blotched 

 with red and with minute opaque white spots ; a large 

 white spot between the apertures on the ganglionic 

 region. Tentacular filaments numerous, long, variable 

 in size, devoid of opaque white. Branchial sac spotted 

 with red, minutely plicated, with the stomata elliptical ; 

 the papillary membranes ample, with the thickened 

 margin narrow and projecting very slightly from the 

 front of the longitudinal rods. Oral lamina well de- 

 veloped, ribbed ; the left oral appendages, four or five 

 simple, diagonal, narrow ridges. 



Lemjtli from three-quarters of an inch to an inch 

 and a quarter. 



Hal). On the under-side of stones, on shells and 

 fuci, in shallowish water, sometimes between tide- 

 marks. 



ENGLAND. Not uncommon on the south and west 

 coasts. Lulworth Cove, Dorset (Jeffreys], Plymouth, 

 Devon (Bate). [Scilly Isles (Cants, 1850).] ' Isle of 

 Man (Alder). 



WALES. --Tenby, Pembroke; and Menai Straits, 

 Carnarvon (Aider). 



SCOTLAND. West coast (Furies). [Hebrides (Alder, 

 186(3). North Uist, Outer Hebrides (Melntosli, 18G5). 

 Island of Housay, Out Skerries, West Voe, Shetland 

 (Nonwni, 18(58).] 



IRELAND. [Irish Sea, not rare (Forbes).~\ Strang- 

 ford Lough, Down (Thompson [and Norman].) [Belfast 

 Lough, Antrim (Thompson, 1840). Clew Bay, Mayo 

 (Thompson, 185(3).] Killery Bay, Galway, on the 

 fronds of Laminaria. (Thompson, Bull, and Forbes). 



First record. [Thompson, 1840.] 



A. scalra is considerably depressed and the test 

 (PI. XV, f. 1) is rather thick- and firm, and is generally 

 attached by the whole side, though somewhat variable 

 in this respect. It varies greatly in the degree of 

 tuberciilation, some individuals being strongly tuber- 

 cular or aculeated over the entire surface, while in 



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