154 Mr. J. Alder on the British Tunicata. 



Ascidia pustulosa, n. sp. 



Body ovate, rugose, horn-coloured, adhering towards the base. 

 Apertures sessile, strongly tuberculated or echinated, reddish ; 

 the anal one terminal, the branchial nearly one-third down the 

 side. Test rather thick, semitransparent, coriaceous, covered 

 with irregular-sized warty or pustulose tubercles, principally on 

 the upper or left side * ; these generally bear smaller tubercles 

 or echinations on their surface : the lower or recumbent side is 

 nearly smooth. Mantle yellowish, blotched with red, especially 

 towards the apertures, and sprinkled with opake white. Tenta- 

 cular filaments few and stout. Branchial sac with rather small 

 papillae : ventral plait smooth. Length about 3 inches. 



I dredged a single specimen of this new species in Fowey 

 Harbour, Cornwall, in the summer of 1847 ; and two specimens, 

 now in the Edinburgh Museum, were got in Lamlash Bay by 

 Prof. Allman. It is readily distinguished from A. mentula by 

 its pustulose tubercles, as well as by its more ovate form. 



Ascidia ohliqua, n. sp. 



Body transversely ovate, light horn-coloured ?, rather rugose 

 when old, but not tuberculated, nearly smooth when young; 

 attached diagonally at the base and partially at the side, leaning 

 over towards the dorsal aspect. Apertures not far apart, conical, 

 with longitudinal grooves corresponding to the angles of the 

 lobes; the branchial aperture not quite terminal, the anal 

 median : ocelli inconspicuous. Test rather thin, transparent, 

 sometimes a good deal covered with zoophytes. Tentacular fila- 

 ments slender. Branchial sac with large subclavate papillae : 

 ventral plait transversely ribbed. Length about two inches. 



Three examples of this Ascidian in different stages of growth 

 were dredged by my friend the Rev. A. M. Norman in 40 to 50 

 fathoms water, off the Outer Haaf, Shetland. The largest of 

 these measured a little above two inches. A somewhat larger 

 specimen was sent to me from Sweden by Prof. Loven, with the 

 name oi Ascidia mentula attached. It has probably hitherto been 

 overlooked as a variety of that species, but it is perfectly distinct : 

 the form is more ovate, the transverse diameter being generally 



* Some difference of opinion exists with regard to the positions of the 

 organs in the Ascidians. I here follow the view adopted by Savigny, 

 Huxley, and others, who consider the side on which the anal aperture is 

 situated to be ventral, and the opposite side dorsal. The right side, on 

 this view, is that on which the viscera are placed. In the Ascidice proper 

 the animal alv\ ays adheres more or less by the right side, thus affording 

 protection to these organs. M. Milne-Edwards considers the vent to be 

 placed on the dorsal aspect : the names of right and left side are con- 

 sequently, in his nomenclature, reversed. 



