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Show 444 MR. W. E. COLLINGE ON EUROPEAN SLUGS. [May 4 brown to pale yellow, when of the latter colour they are usually more intense in the region of the caudal pore. Long. max. 40-55 millim. There is a single vestibule, from which the sperm-duct opens in the form of an expanded tube; it is comparatively larger than in A. subfuscus, and is folded upon itself at the point where the vas deferens commences, which organ is also considerably longer than in A. subfuscus (Pis. X X X . & X X X I . figs. 13-14). The free-oviduct is a long, wide, and somewhat S-shaped tube. In none of the specimens 1 have examined does it approach the form so characteristic of A. subfuscus (Pl. X X I X . fig. l,fov.). The retractor muscle is attached about the middle, whereas in subfuscus it is attached to the upper third. The receptacular duct is long andthin, expanding at its head into the spherical receptaculum seminis. The retractor muscle is attached to the duct just below the head. The common duct is thrown into a series of convolutions terminally, and shorter than in subfuscus. The hermaphrodite gland is a small, dark-coloured, ovoid or pyriform body with a long convoluted duct. Babor's description of the reproductive organs of A. citrinus, Wester. (2), leaves no doubt as to it being Midler's A. fuscus. I have reproduced his careful figures of these organs (PL X X X I. figs. 15-16), and also those of the variety boettgerl, Poll. (PL X X X I. fig. 17), which according to this author is characterized anatomically by the short receptacular duct, a feature which I can confirm. 5. Description of a new Species of Arion. In 1892 (5) I recorded a new variety of the well-known Arion hortensls, Fer., under the name of cceruleus. The specimens had been very kindly sent to me from Ireland by Dr. R. F. Scharff. I pointed out in the description of this variety that possibly, when further investigated, its anatomical characters might prove to be more permanent than I then supposed. Since that date specimens have been sent to m e by Mr. B. B. Woodward from Ealing (10), by M r . H . Horsman Macnabb from Heaton, Lancashire, and I have myself collected examples near Oxford and elsewhere. After having made a careful examination of this material, I feel convinced that this form is sufficiently distinct both externally and internally to be separated from A. hortensls, Fer., as a distinct species. ARION CERULEUS, sp. nov. Arion hortensls, Fer., var. cosruleus, Collinge, Conchologist 1892, vol. ii. p. 26. Body blue or greyish blue, with conspicuous dark blue lateral bands, and pale yellow ground-colour between these and the foot-fringe ; mantle with dark bluish central patch, and darker bands at each side; head and tentacles bluish grey; foot-fringe white, usually without lineoles ; foot-sole white or very pale yellow; rugae flat, large, and elongated; sulci dark. Length (in alcohol) 27-33 millim.; alive 43 millim. |