THE BRITISH SPECIES OF TESTACELLA. 



By WILFRED MARK WEBB, F.LS., 



Staff-Demonstrator in Biology to the County Council of Essex. 



It is now recognised that there are three species of Testacella 

 to be met with in this country, to wit, Testacella iiiangei, Ferussac, 

 T. haliotidea, Draparnaud, and T. scntulum, G. B. Sowerby. Of 

 these molluscs, the two last are, at first siglit, so much alike, that 

 until recently, any shell-bearing slug not referable to Ferussac's 

 species was put down as T. haliotidea. 



The history of the separation of the third species is as 

 follows : — 



1823. In this year Mr. G. B. Sowerby* described Testacella 

 scntulum as a distinct species, but, following the opinion 

 of Ferussac, British conchologists, including Sowerby 

 himself, came to consider this form to be merely a 

 variation of Draparnaud's species. 

 1856. Mr. Tapping! re-described the species under the name 

 of T. medii-tempii, his specimens being found in the Middle 

 Temple gardens. 

 1885. The following is an extract from a letter written by the 

 late Mr. Charles Ashford to the writer, with reference 

 to the anatomical work on which the following paper 

 was founded : — 



" The results of the examination of T. scntulum were 

 " communicated to Mr. Taylor by letter. The first 

 " specimen, received through Mr. Roebuck and sent me 

 *' at Mr. Taylor's request, was dissected in February, 

 " 1885, and was found to differ materially from Moquin- 

 " Tandon's figure of T. haliotidea. Subsequent examples 

 " sent me by Mr. Taylor showed the difference to be 

 " constant." 

 1 888. The paper | to which the credit of re-establishing 

 Sowerby's species really belongs was published in this 



* Genera of Recent and Fossil Shells. i8::3. PI. clis. 

 t Zoologist, 1856, p. 5105. 



On the specific distinctness and geographical distribution of Ta/.ir lla xc/i/iiluno 

 G. B. Sowerby. Journ. of Conch., vol. v., 1888, p. 337. 



