INTRODUCTION. 17 



In 1863 Mr. Joshua Alder published, in the ' Annals 

 of Natural History ' [ser. 3, xi], " Observations on the 

 British Tunicata," in which the following twenty-two 

 new species are described: Ascidia pustulosa, A. 

 obliqiKt, A. i-iidis, A. plebeia, A. ctGuleata, A. pulchella, 

 dx sorialis, Cyittltin sguamulosa, G. rosea, G. sul- 

 , C. granulata, G. opalina, G. violacea, G. glomerata, 

 Thylacium Xornuuii, T. variegatum, PolycUnum suc- 

 c'uieum, P. cerebriforme, Amaroecium papillosum, P<ir*- 

 cidia flabellata, Botrt/lloides sparsa, and B.pusilla; and 

 two other species [Amar'oecium pomum and Distoma 

 rifrenm of Sars] are for the first time recorded as 

 British. [The name Cijntltin <-<>ni<it is also newly pro- 

 posed for the G. ampulln of Forbes, not of Bruguiere ; 

 and for two species, considered to have been referred 

 in error to Savigny's Sidnyum turbinatum, the names 

 S. Flemingii and S. Forbesii are proposed.] Remarks 

 are made on seven other species and on several genera, 

 and the spiral arrangement of the minute vessels of 

 the branchial sac in Ascidia [Gorella] pafallelogramma 

 and Molgulu arenosa is described and figured. 



From the above summary, exhibiting the sequence 

 of the discovery of the British Tunicata, it appears 

 that up to 1863 one hundred and six* species stand 

 recorded. Since that date several more have occurred, 

 chiefly by the exertions of our friends, and more par- 

 ticularly by the never-ceasing research of the Rev. A. 

 M. Norman and Mr. J. Gwyn Jeffreys. The researches 

 of Mr. Norman have not only added new species to the 

 list, but have also very materially increased our know- 

 ledge of their distribution in the British seas. We are 

 indebted to many other eminent naturalists for similar 

 services, amongst whom we have pleasure in mention- 

 ing our friends Dr. J. S. Bowerbank, Prof. Allman, the 



* " Ninety-nine " in the authors' MS., biit to the 73 in Forbes and 

 Hanley's ' British Mollusca ' must be added Molgula citrina (1848), M . 

 siphonata (1850), Thylacium Sylvani, Didemnum candidum, D. gelatinosum, 

 and Amaroucium edentulum (1851), Clavelina producta and Amaroucium 

 albicans (1856), Cynthia vestita (1860), and the 24 records of Alder (1863). 

 All these additional species are included in this Monograph. 



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