INTBODUCTIOX. 15 



interesting though somewhat neglected branch of mala- 

 cology, and the genera and species are all well and 

 fully described. 



In the ' Catalogue of the Mollusca of Northumberland 

 and Durham ' published in the ' Transactions of the 

 Tyneside Naturalists' Field Club ' in 1848, the authors 

 of this Monograph enumerated thirty-one species of 

 Tunicata; of these sixteen are simple Ascidians, one is 

 a social Ascidian, and fourteen are compound Ascidians. 

 In all thirteen were for the first time described and 

 named, as follows : Gi/uthiti corinren, Molgula nrenosa, 

 M. citrina, Ascidin xurdida, A. nlbiild, A. <lrjn-rxx<t, A. 

 elliptica, A. pellucida, Botryllus rulxins, B. r//v'.sw//x, B. 

 castnneus, Botri/lloides radiatn, and B. ranudo^i. 



[In 1850 Mr. Joshua Alder added to these, in his 

 "Additions to the Mollusca," etc., in the same publica- 

 tion, a new species, Molgula siphonata; and in 1851 

 Forbes and Goodsir (' Trans. Roy. Soc. Edinb.,' xx) 

 described a new species, Sy-utetliys hebridicus,from the 

 Hebrides. In this year, also, the " Zoology of the 

 Scilly Isles ' : by Victor Cams, appeared (' Proc. 

 Ashmolian Soc.,' Oxford, vol. ii). In it Cams records 

 fourteen Tunicates and founds a new genus, TIn/lrinm, 

 describing as new species TJu/lcn-lmn NV//V//// and 

 Amareucium edentulum, and also adding to our fauna 

 Didemnum candidum and I), gelatmosum. 



In the second volume of Forbes and Stanley's 

 ' British Mollusca ' (1849), twelve of Alder and 

 Hancock's species of 1848 are introduced, including 

 Molijula arenosa substituted for J/. tu.l>id<jx<i of their 

 first volume, M. citrina being omitted ; and in the 

 fourth volume (1852) Syutetlujs hebridicus is added. 

 In this volume, also, there is the first notice of the 

 occurrence of Appendicula/ria in our seas, as having 

 been found "off the north coast of Scotland in 1845," 

 but the name of the species is not given. It was 

 probably A. ftacjellnm, Cham., which was recorded from 

 Tenby (as A. flabellum) by Professor Huxley in 1856 

 (' Quart. Journ. Micr. Sci.,' iv). The number of species 



