collinge: a review of the arionid^: of the British isles. Si 



Anatomy. — The digestive system resembles that of Avion. The 

 reproductive organs are very characteristic. There is a well 

 developed retractor muscle which has its attachment just where the 

 vas deferens opens into it. The vas deferens is much larger than in 

 Arion, and the oviduct shorter. The penis is very long and consists 

 of the largely- developed duct of the receptaculum seminis. 



Reproduction. — From the observations of Signor de Silva 

 e Castro the eggs are transparent and exceedingly large, measuring 

 from 5 to 7 mm. long and 3 mm. broad (41). 



Habitat. — Dr. Scharff, who has collected this slug in its natural 

 habitat, says he found them among lichens, "The dark grey lichens, 

 with the white or yellowish fructification, conceal the slug perfectly, 

 and there is no doubt that we have here a most striking instance of 

 protective colouring." 



The species has been figured by Allman, Heynemann, Scharff, 

 Forbes and Hanley, Jeffreys and Rimmer, the last three being 

 I presume, copies of Allman's figure. The best illustrations are 

 those of Scharff and Heynemann. There are also figures of the 

 anatomy, Dr. Scharff informs me, in Ann. and Mag. New York 

 Lyceum of N.H., vol. xi, 1874, in a paper by Binney (the figure is 

 completely wrong, I am informed), and also in Godwin-Austen's 

 " Land and Freshwater Mollusca of Lndia," pi. xii. 

 BIBLIOGRAPHY. 



1 Allman, G. J. — " Description of a new genus of Pulmonary 



Gasteropod." Ann. and Mag. N".H., vol. xvii, 1846. 



2 Baudon, Aug. — "Me'moire sur les Limaciens du Departement 



de l'Oise." Beauvais, 1871. 



3 Cockerell, T. D. A. — " Arion sub/uscus" Science Goss., 



p. 1 14, 1886. 



4 Do. " On the Geographical Distrib. of Slugs." Proc. Zool. 



Soc, p. 214, 189T. 



5 Do. " The Genera Li/nax, Arion, and Helix.' 1 '' The 



Conchologist, vol. II, p. 28, 1892. 



6 Do. " Mollusca Notes." Brit. Nat., p. 101, 1891. 



7 Do. " A. circumscriptus, Johnst, = bourguignati, Mab." 



Brit. Nat., p. 20, 1891. 



8 Do. " Notes on A. hortensis, A. circumscriptus, and their 



allies." The Conchologist, vol. i, p. 33, 1891. 



9 Do. "Notes on Slugs, chiefly in the Collection at the 



British Museum." Ann. and Mag. N.H., p. 277 

 and 380, 1890 ; p. 97 and 328, 1891. 

 10 Collinge, Walter E. — "Notes on the Variation of the Genus 

 Arion, Fer." Ann. and Mag. N.H., vol. ix, 

 p. 307, 1892. 



