164 Mr. J. Alder on the British Tunicata. 



me that it has been erroneously referred to his Ascidium (the 

 Ascidia ampulla of Bruguiere). That species is described to be 

 thickly covered with minute hairs hooked at the points, and has 

 the tubes granulated or shagreened, in neither of which cha- 

 racters does the present species agree with it : nor does Baster's 

 Ascidium appear to be coated with sand — a character so remark- 

 able in C. comata, from the depth to which it is generally co- 

 vered. This arises from the great length of the glandular hairs, 

 and is especially the case in old individuals, where the hairs are 

 much branched and become thickened at the base, giving the 

 test a peculiar appearance when the sand is removed. 



This and the following species belong to the Glandula of 

 Stimpson *, a genus separated from Cynthia on account of the 

 individuals being unattached. As this character, however, is not 

 corroborated by any structural difference, and is also found in 

 some species of other genera, we have not thought it desirable 

 to give it generic rank. 



Cynthia glacialis, Sars. 



Body orbicular or ovate, a little compressed, unattached, and 

 entirely covered with sand and fragments of shells. Apertures 

 approximated and slightly tubular when expanded, inconspicuous 

 when withdrawn, of a dull, semitransparent white. Test smooth, 

 whitish, soft and rather thin, a little wrinkled towards the 

 apertures, apparently without hairs, the shelly fragments ad- 

 hering directly to the skin. Mantle transparent and nearly co- 

 lourless. Tentacular filaments simple, linear. Branchial sac with 

 four folds on each side. Ovaries in parallel cylindrical masses, 

 extending transversely, about four on each side. Diameter 

 rather more than half an inch. 



Two specimens were obtained from the fishing-boats at Craster, 

 Northumberland, by Mr. J. Stanger, in 1860; and it has since 

 been dredged on the northern part of the same coast. 



Believing this species to be undescribed, I had proposed for it 

 the name of C. vestita, under which appellation its discovery was 

 announced by Mr. Stanger in the ' Transactions of the Tyneside 

 Naturalists' Field Club' (vol. iv. p. 335). I have since found 

 that Prof. Sars had previously met with it on the coast of Nor- 

 way, and had published a notice of it under the name of Glandula 

 glacialis (Forhandl. i Vidensk. Selsk. i Christiania for 1858). 



Cynthia opalina, n. sp. 



Body transversely ovate, strongly but irregularly mammillated, 

 opaline white, attached by a broad base. Apertures not far 

 apart, rather large ; the branchial one placed not far from the 



* Proceedings of the Boston Society of Natural History for June 1852. 



