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Show 1897.] MR. W. E. COLLINGE ON EUROPEAN SLUGS. 441 gations upon two common and widely distributed species, viz., Arion subfuscus, Drap., and A. hortensls, Fer., which are detailed below. ARION SUBFUSCUS, Drap. The form and position of the generative organs in this species are illustrated on Pl. X X I X . fig. 1. Externally the species is one subject to a wide range of variation. I have myself noted some thirty minor colour-variations in addition to the fifty or sixty varieties which have been described by various authors. If this species assumes different colours, markings, &c. in different districts, which it undoubtedly does, in common wdth nearly all other species, the value of such as distinctive features is materially lessened, and one is led to ask " Does the form of the generative organs vary to a similar extent ? " I have examined 152 lots of this species, each from different localities in various parts of Europe, including in all 751 specimens. All of these were adult and collected during the months of July and August in 1892-3-4-5. Out of this large collection in only four of the lots were variations found, particulars of which are as follows:- 1. Four specimens collected at Southampton (Pl. X X I X . fig. 2). In three specimens the sperm-duct had a globose ring-like swelling at its commencement, and the free-oviduct showed the globose form figured. Professor Simroth, who examined a specimen, considered it " a very developed A. subfuscus:' 2. Three specimens from Ireland (Pl. X X I X . fig. 3). All slightly smaller and darker than the typical form. All three specimens exhibited a slight difference in the form of the free-oviduct. 3. Five specimens collected near Knowle, Warwick (Pl. X X I X . fig. 4). All belonging to the variety griseus, Cllge. In one specimen the form of the free-oviduct wras somewhat like that in No. 1 (fig. 2), only less globose and more constricted in the middle of the lower portion. 4. Five specimens collected in Northern Italy (precise locality uncertain). In two specimens both the sperm-duct and free-oviduct differed slightly (PL X X I X . fig. 5). In all the above variations it will be seen, on comparing figures 2 to 5 with figure 1, that the distinction between the upper and lower portion of the free-oviduct wras very sharply marked. ARION HORTENSIS, Fer. Only 83 lots of this species have been examined, each from a different locality, including in all 491 specimens. In 19 specimens the generative organs were found to be immature, thus leaving 472. Variations were found in six cases. 1. T w o specimens from Tuxford, Newark (Pl. X X X . fig. 7). In one the free-oviduct was longer than usual and the sperm-duct more globose. 2. Ten specimens from Ireland (Pl. X X X . fig. 8). Three speci- |