EABOR : NOTE ON ARION CITRINUS, WESTERLUND. 47 



ponderance of the one sex above the other. From this I should 

 infer that the above-mentioned condition of the oviduct is 

 cliaracteristic of citriniis only; unfortunately, the whole description 

 is from one specimen only. This character is, of course, in no way 

 sufficient for a species, but for a variety of the typical fiisais, as 

 Pollonera'* an(i Collinge'' have already suggested ; but it seems to 

 me that there are already too many unnecessary species of the 

 subjtiscus group, and that an endeavour should be made to reduce 

 them to a few characteristic species. In this case citrinus would 

 probably deserve the rank of a subvariety of si/hfiistus, and fuscus 

 as a variety, for I must agree with the opinions of Simroth'" and 

 Collinge,'' that there are not sufficient grounds to rank fuscus as 

 an independent species. A. subfuscus, there can be little doubt, 

 is a good species, both from its external appearance, especially its large 

 size, described by Pollonera,^' " and from its anatomy, especially the 

 form of the oviduct, so clearly stated by Collinge'- and figured by 

 Scharff.'^^ 



I will linally add that the var. boeitgeri, Poll., oi ficscus is always 

 characierised anatomically by a short receptaculum that hardly 

 reaches to the ovisperm duct, and does not grow with it, as we 

 find in subfuscus and fuscus, which character Pollonera figures," but 

 makes no mention of it in the text, although it is constant and 

 rather significant. 



Description of Plate I. 



Illustrating Mr. Joseph Eabor's paper, "Note on Arion citrinus, Westerlund. 



Fig. I. — Reproductive organs oi Avion citrinus, Westerl. \ 

 Fig. 2. — Their terminal ducts from the opposite side. ''^- 

 Fig. 3. — Inside portion of the oviduct in part x x fig. 2. 

 Fig. 4. — The terminal ducts of the \.)']f\cz\. fuscus, Miill 

 Fig. 5. — The terminal ducts oi A. fuscus v. boettgeri. Poll. 



'■* Bull. Mus. Zool. Anat. Conip. Torino, 1890. 



•' Coiichologist, 1893, vol. ii., pp 113-17. 



'" Loc. cit. 



" Atti liella R. .Ace. d. Sci. Torino, iSgi. 



'■-' Ann. Mag. Nat. Hist., 1894, vol. xiii., pp. 66-7, pi. v. .\. 



'■■' Trans. Roy. Dublin Sec, Ireland, iSyi. 



' ■* .Vbh. 1.1. Naturf Vtreine zu 15remen, 1884. 



