jMONOGRAPII of BRITISH LAND ANK FUESIIWATER MOLLUSC A. 



139 



Milax gagates (Draparnaud). 



1801 Limax gagates Draparnaud, Talil. Moll, p. 100, no. 1. 



1805 — — Draparnaud, Hist. Nat., p. 122, pi. 9, f. 1, 2. 



1824 — maiirus Quoy & Gaimard, Voy. I'ranie, p. 426. 



1855 — (Amalia) gafjates Moquin-Tandon, Hist. iMoll., vol. 2, p. 19, pi. 2, f. 1- 



1872 — hcwstoni Cooper, Proc. Acad. Nat. Sci. Pliilad., p. 147, pi. 3. 



1855 Milax ciagates Gray, Catal. Pulni., p. 174. 



1880 — tasmanicus Tate, Proc. Roy. Soc. Tasmania, p. 10. 



1876 Amalia marqinata niut. qafjates Pini, Bull. Soc. Mai. Ital., vol. 2, p. 107. 



1897 — babori Collinge, Proc. Mai. Soc. , p. 294. 



I STORY. — Mildx gn gates (gagates, 

 jet), i.s one of our more uncoinmou 

 slugs, and though typically of jet 

 black hue, is in this country more fre- 

 quently found of a pale plumbeous or 

 brownish tint. 



This species was first described by 

 Draparnaud in PSOl, and was first dis- 

 covered in Great Britain by Mr. R. D. 

 Darbishire, B.A., F.G.S., of Victoria 

 Park, Manchester, who in September 

 1851, found a characteristic specimen 

 at the foot of a hawthorn hedge, on the 

 Lsle of Portland, which was identified 

 by Prof. Forbes. 



Mr. E. A. Smith, in the Proc. Zool. 

 Soc, 1884, p. 276, suggests the proba- 

 bility that the L. capensis Krauss may 

 prove to be referable to our species ; 

 and Mr. C. T. Musson makes a similar 

 suggestii.iu in reference to the L. pectinatus of Selenka. 



Prof. R. Tate has described (Proc. Roy. Soc. Tasmania, 1880, p. 16) a 

 Milax niqrkolus, which inhabits the gullies of the Adelaide hills, and is 

 widely dispersed over the Adelaide plain generally. Though presented as 

 a new and probably in<ligenous species, the author suggests that it may be 

 identical with Milax gagates. 



Dr. Simroth considers Amalia doderlelnl, A. skula, and A. Insular is as 

 all synonymous with the present species, and agrees with Heynemann 

 in similarly regarding Llmax scaptobhis of Bourguignat, but as there 

 appears to be some confiict of opinion on the subject, their views are 

 simply recorded here. 



Diagnosis. E.^ternallt, Milax gagates is known from its congener 



by its nKjre uniform colouring; by the keel being usually of the same or of 

 a' darker tint than the body, and by its greater prominence at the caudal 

 extremity ; the parallel longitudinal groovings of the body are also quite 

 unpigmented, and the intervals between the groovings smooth or deli- 

 cately granulate. 



Internally, it is sharply differentiated by the globose spermatheca and 

 the protuberant atrium or vestibule. 





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