532 SciiARFF— 0« the Slugs of Ireland. 



External Characters. — A. carinata is at once distinguished from all the pre- 

 ceding species by the prominent ridge or keel running from the posterior 

 margin of the mantle to the end of the body. A less conspicuous feature, by 

 which this and the next species may be distinguished from all others, is the 

 horse-shoe shaped groove on the mantle. In A. carinata this groove is almost 

 always filled with a black jjigment, so as to render it more readily visible than 

 in the next species. Some authors have thought it advisable to create a separate 

 name for specimens in which the black marking meets in front to form a complete 

 horse-shoe. However, I have examined a large number of sj^ecimens from gardens 

 in Dublin where it is, after AgrioUmax agrestis, the commonest slug, and I found 

 that in full}- 20 per cent, the horse-shoe marking is complete, i.e. unites in front. 

 In some sjjecimens there was only a faint indication of any marking at all ; in fact, 

 it is a feature which is not by any means constant. I noticed also that in those 

 20 per cent, in which the black pigment extends all round the groove, the general 

 body-colour is darker than in the others. 



The body-colour in this species varies from yellowish brown to dark brown, 

 the sides getting lighter towards the foot. The inter-space between the wrinkles 

 is generally marked by darker pigment, and the mantle is granulated. The head 

 and tentacles are of a bluish colour, sometimes purple, and the keel is almost 

 always lighter than the body-colour on each side of it. 



The largest specimen taken measured 65 mm. long, by 10 mm. broad. 

 Moquin-Tandon's (26) Limax marginatus, which is jDrobably this species, never 

 exceeds 60 mm. in length in France. 



Anatomy (Plate LVIL, fig. 30). — There are the four convolutions of the intestine 

 as in Agriolimax, but without a coecum. The upper portion of the reproductive 

 organs are like those of Agriolimax, but in the lower parts, important differences 

 appear. The receptaculum seminis {rec.) is very large, equalling the free oviduct 

 {ov.) in length. Its lower part is wide, but it becomes attenuated in its upper 

 portion. What appears to be the penis is in reality the jjortion of the sperm-duct 

 in which the spcrniatophore is formed [j^at.]] the lower portion only can be looked 

 upon as a penis ()?.). Both penis and oviduct, as well as the receptaculum, open 

 into a short vestibule or atrium {Iv.) wiiich, according to Simroth (38), is everted 

 during copulation. A number of large accessory glands {ac.) also open into the 

 vestibule by means of delicate ducts. 



lleproduction. — The fact that hardly any of the text-books referred to, give a 

 description of the eggs of this species shows that they have rarely been observed. 

 Although I kept a large number of specimens in captivity from the middle of 

 September to the end of the year, none of them deposited eggs. Simroth (38) is 

 the only author who refers to the ova of Amalia margiiiata, which is either the 

 same or a closely allied species to ours. He states having observed them at the end 



