46 BABOR : NOTE ON ARION CITRINUS, WESTERLUND. 



duct is rather short and convoluted several times at the end. The 

 albumen gland and ovisperm duct are similar in appearance to those 

 found in fuscus and subfuscus, Drap., but the terminal ducts are 

 rather remarkable. The rather long vas-deferens (sperm-duct, Scharff) 

 passes in the middle of its length into the portion of the penis in 

 which the spermatophore is formed ( = the Patronenstrecke of 

 Sim roth 3 and sperm-duct of Collinge) 4 fi entering with its rounded 

 end into the atrium (vestibule) together with the receptacular duct. 

 The receptaculum seminis has a rounded ampulla (head of recep- 

 taculum seminis) which is closely connected with the ovispermduct 

 at the point of its division. The duct is long and thin, expanding 

 suddenly at its base. The free oviduct is short and muscular, so 

 that from its beginning it is rather thick and only becomes larger 

 towards the orifice ; in almost its first third there is a small protuber- 

 ance to which is attached one slip of the retractor muscle, which 

 soon joins with the other slip inserted on the ampulla of the 

 receptaculum seminis. The wall of the oviduct forms on its inner 

 side two strong and two weaker longitudinal thickenings ; these in 

 the upper half are divided into a greater number of thinner ones, 

 but pass along the whole 'length of the free oviduct. In this respect 

 citrinus differs from fuscus, which has the upper half or third of the 

 oviduct — viz., above the insertion of the retractor muscle — thin ; 

 membraneous and without the inner thickenings (Langswiilste 

 Simroth), which in fuscus are developed in the lower part only — 

 viz., beneath the insertion — and that in a reduced number of two 

 {fuscus and brunneus, Lehmann) or at most three, the additional one 

 being very weak (rarely in fuscus, common in subfuscus). 



One may be inclined to consider this formation of the oviduct 

 as a standard of the development of the genital organs, which, as 

 I have convinced myself,' 1 : are undergoing, according to the phases 

 of the sexual function, rather remarkable modifications, even in 

 animals which have reached their full size. But I cannot accept 

 this explanation, for numerous specimens of fuscus collected at the 

 same time with this citrinus fully agreed with it in the develop- 

 ment and size of the individual organs, so that it was impossible 

 to observe in any of them (or in the described citrinus) a pre- 



:1 Zeit. f. wiss. Zoo]. 1S85, Bit. 42. 



4 Conchologist 1892, \ol. ii., pp. 56-^6. 



6 Ann. Mag. Nat. Hist., 1893, vol. xii. , pp. 252-4. 

 ' Sitz. Gcsd. d. wis-. Math. -Nat. Prag., 1893. 



7 Verghl. d. Deutsch. Zool. Gesel. Leipzig, 1894. 



