552 ScHAEFF — On the Slugs of Ireland. 



Paper on this species, are much better than Allman's original drawings, in spite of 

 the fact of tlie latter having been executed by so able a draughtsman as tlie late 

 Mr. Du Noyer. Du Noyer's figures are pretty, but idealized. The only point in 

 Heynemann's figures which I take exception to is the caudal portion of the body. 

 This should not be so flat, but more raised as in my figm-e 2-t. Forbes and 

 Hanley (9), Jeffreys (16j, and others, seem to have merely copied Allman's 

 figure. 



This slug was discovered in the county Kerry, in the autumn of 1842, by tlie 

 late William Andrews of Dublin, who placed it in the hands of Dr. Allman ; and it 

 was first exhibited at a meeting of the Dublin Natural History Society in January, 

 1843. The skin is always smooth and shiny, and not black, but of a dark gray 

 colour. 



Both on the mantle and back there are a series of yellowish-white or yellow 

 spots. These seem at first sight quite irregularl}^ placed on the body, but Sim- 

 roth (39) has drawn attention to the fact that on closer inspection there appear 

 traces of distinct longitudinal bands, as in Avion. In most cases, indeed, I have 

 observed these very well, but in others the banding is very difficult to demonstrate. 

 The margin as well as the sole of the foot are of a dirty white. The tips of the 

 tentacles are cylindrical, whilst in the genus Arion they are round. The mucus is 

 transparent and limpid. The largest specimen measured about 55 mm. in length. 



Mabille (23), in his Paper on the genus Geomalacus, referred to on p. 551, has 

 attempted to set up a second species, which he calls G. andrewsi. His assumption 

 is based on Allman's original description, who mentions, besides the common form, 

 a white-spotted variety. Mabille believed that this meant a white, spotted variety, 

 i.e. a white slug with black spots, and, astounding as it may appear, proceeded on 

 these grounds to describe it as a new species. 



Anatomy (Plate LVII., fig. 37). — Heynemann(13) does not deal with the anatomy 

 of this slug, excepting in a reference to the shell and the tongue, neither of which 

 is of very great importance. The latter is very much like that of an ordinary 

 Arion, but the shell is firm and regular like that of a Limax. 



The fact that the calcareous particles often congregate together in Avion 

 intevmedius, and form a kind of irregular shell, has induced French authors, such 

 as Mabille (23) and Baudon (2), to start the idea that this slug must be a 

 Geomalacus ; but the shell in the genuine Geomalacus is of a very different nature. 

 The intestine resembles that of Arion, but the reproductive organs differ widely. 



The penis {p) is formed by the enormously developed duct of the receptaculum 

 seminis {vec), and not by the oviduct, as in Avion. There is a long retractor 

 muscle [rm.) attached to the penis at the part where the sperm-duct opens into it. 

 The sperm-duct {sp.) is vcrv much longer than in any Arion, whilst the ovisperm- 

 duct {ps.) is shorter. 



