ScHARFF — On the Slugs of Ireland. 527 



External Characters. — As a rule Agriolimax agrcstis may be distinguished from A. 

 laevis by the colour alone. The former is almost always of a dirty yellowish-white 

 colour (fig. 5), either with or without diffuse patches of a darker pigment. The 

 latter may altogether obscure the original body-colour, and produce a bluish slate- 

 coloured slug (fig. 6). I have had two specimens from the Aran Islands, county 

 Galway, which resembled A. laevis in so far as they were of a dark chocolate colour, 

 but the milky slime, the short mantle, and the more pronounced keel were sufficient 

 to pronounce them as mere varieties of A. agrestis. Anatomically they differed in 

 no way from the usual form. 



A. agrestis grows to a much greater size than A. laevis, the largest specimen 

 measuring 40 mm. by 5 mm. According to Moquin-Tandon (2G) it reaches the 

 length of 60 mm. in France. 



In a fully extended specimen the mantle occupies exactly a third of the total 

 length of the body, which is somewhat compressed posteriorly, and there is a well- 

 marked keel reaching from the posterior third to the end of the body. The head 

 and tentacles are faintly violet-coloured, but vary according to the general body 

 tint. 



Quite fifty per cent, of the varieties I picked up during the summer in the 

 country near Dublin were of a uniform yellowish-white, the space between the 

 wrinkles being marked by a very light gray, so that the shape of each body- 

 wrinkle was well seen. Once I obtained a perfectly white albino specimen under 

 a heap of hay at Raheny. In November 60 per cent, of the A. agrestis in my 

 garden were of a yellowish-white colour, faintly speckled with gray. On the other 

 hand, of those obtained at the same time from the Aran Islands, 80 per cent, had 

 the ground colour reddish-yellow, but they were uniformly mottled with dark gray, 

 two specimens being almost black. The mucus in this slug is very abundant, and 

 of a milky colour. 



Anatomy. (Plate LVIL, fig. 28). — There are only four convolutions in the 

 intestine of this species and the next, as has been shown by Nunneley (31), and more 

 recently by Simroth (38). But Nunneley did not notice the small coecum near the 

 terminal convolution of the intestine. Simroth pointed out that it is not homologous 

 with that in Limax, being differently situated. The hermaphrodite gland (Jig.) is 

 elongated, and generally the acini composing it are split up like a bunch of grapes. 

 The hermaphrodite duct (hd.) is almost always straight, i. e. not convoluted like 

 that in Limax. Close to the genital pore, the ovisperm-duct (os.) divides into 

 oviduct {ov.) and sperm-duct (s/;>.). The latter is short and opens into the very large 

 penis {p.). The receptaculum seminis {rec.) is placed at the junction of the penis 

 and oviduct. Near the opening of the sperm-duct into the penis, an accessory gland, 

 the flagellum (/.), opens into it also, and I found this to vary somewhat in the 

 different specimens I examined. 



