ASCIDIA ELLIPTICA. 141 



when young, attached throughout its whole length. 

 Apertures, branchial terminal, papillose, very little 

 elevated, and divided into eight tubercular segments ; 

 anal situated a little below the branchial, rather promi- 

 nent, with six tubercles. Ocelli rather inconspicuous. 

 Tt'st tough, sub-opaque, transparent when young, 

 slightly tuberculated towards the apertures. Maiitlf 

 opaque, white or flesh-coloured, with a few red spots 

 between the apertures. Tentacular filaments rather 

 long. Branrliial sac with small primary, but no inter- 

 mediate papillae. Oral lamina strongly ribbed on the 

 right side. 



Len</tli three quarters of an inch. 



Hab. On the under-side of stones at low water- 

 mark. Common on most parts of our coast (Furies). 



ENGLAND. [Bristol Channel (Forbes). ~\ Cullercoats, 

 Northumb. (All'i-). [Isle of Man (Furies).'] 



SCOTLAND. [Bast and west coast (Forbes). Leith 

 shore, Firth of Forth (Jameson, 1811).] Firth of Clyde 

 (Norman). [Hebrides (Forbes, 1850). Allans, Cum- 

 brae (Norman, 1857).] Shetland (Forbes). [(Lerwick, 

 Shetland Isles, 1861 (Norman, 18(58).] 



IRELAND. [Strangford Lough, Down; and Belfast 

 Lough, Antrim, dredged (Thompson, 1840).] 



First reconL Alder and Hancock, 1848 [(Jameson, 

 1811, as Axt-'ul'ni prunum)~\. 



The test (PI. XVI, fig. 4) appears to contain but 

 few blood-channels ; at least not many were observed. 



The mantle (PI. XVI, fig. 5) is well supplied with 

 muscular fibres, which, in the centre, are loosely woven 

 in various directions ; but around the margin there is 

 a broad belt of parallel fibres which converge towards 

 the centre in pretty-regular order. 



The branchial sac (PI. XVI, fig. 6 and 7 ; PL XVIII, 

 fig. 11) is rather delicate, and is minutely plicated as it 

 is in most species of the genus, only here the plicae are 

 wider than usual. The primary vessels are a little 

 variable in size, and the secondary rather long with 



