22 Mr. W. E. Collinge on the 



has figured and described the generative system of most of 

 the slugs found in this country, and I have more recently 

 described * the same system in a number of Arions not found 

 in Irehind or not known as occurring in the British Islesat 

 the time Dr. Scharff wrote. A similar description, with 

 figures of the Testacellcn, is, I think, desirable. 



My best thanks are due to Mr. J. G. C. Taunton, of Mason 

 College, for the abundance of material which he has been 

 good enough to procure for me, and also to Messrs. Morris 

 Young, E. W. Swanton, and Charles Oldham for specimens 

 which they from time to time have favoured me with. 



Testacella haliotidea^ Drap. (PI. I. figs. 1 and 4.) 



It will be unnecessary to dwell at any length upon the 

 system in more than one species, as it is one of comparative 

 simplicity. I shall therefore describe in detail the individual 

 organs in this species, and point out in the two following ones 

 the various differences and modifications, and then briefly 

 compare the three. 



The vestibule opens into a dilated vagina, from which the 

 receptacular duct is given off". At the point of juncture of 

 the vestibule and vagina the penis passes off; it is a long 

 curved organ, the anterior portion of which is sometimes 

 dilated in a somewhat ceecal-like form, as shown in PI. I. 

 fig. 4. This must not be regarded as the typical form of the 

 penis. I would specially draw attention to this fact, as it 

 has been figured and described as such t and certain compa- 

 risons instituted between the form of the organ in T. lialio- 

 tidea and T. sctUulum. A reference to Lacaze-Duthiers's 

 well-known paper and accurate figures { supports my state- 

 ment. The direct continuation of the penis is the vas 

 deferens ; from the point of juncture of the two organs a long 

 dilated flagellum is given off laterally. In the paper just 

 cited Mr. J. W. Taylor very wrongly describes the vas 

 deferens as passing off laterally from the penis and flagellum, 

 whereas, as previously stated, the vas deferens is a direct 

 continuation of the penis. In none of the European Testa- 

 cellce which I have examined does the vas deferens differ in 

 its relation to the penis from the same organ in any other 

 slug ; that is to say, although it may externally appear to 

 pass off from the penis as a lateral tube, morphologically it is 



* ' Concliologist,' 1892, vol. ii.pp. 66-G6and 76-83; also 1893, vol. ii. 

 pp. 113-117. 



t Journ. Oonch. 1888, pp. 337-347. 



i Arch, de Zool. exp. et ggn. 1887, vol. v. pp. 459-596, 12 pis. 



