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 Ireland or not known as occurring in the British Isles at 
the time Dr. Scharff wrote. A similar description, with 
figures of the Testacelle, 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 cecal-like form, as shown in Pl. I. 
fiz. 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 | and certain compa- 
risons instituted between the form of the organ in 7. halio- 
tidea and T. scutulum. 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 Huropean Testa- 
celle 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 
* ¢Conchologist,’ 1892, vol. ii. pp. 56-66 and 76-83 ; also 1893, vol. ii. 
pp. 118-117. 
+ Journ. Conch. 1888, pp. 337-347. 
¢ Arch. de Zool. exp. et gén. 1887, vol. v. pp. 459-596, 12 pls. 
