54 JOURNAL OF CONCHOLOGY, VOL. l6, NO. 2, AUGUST 30, I919. 



the vas becomes the penis. Arising from the free oviduct, 

 immediately below the beginning of the glandular portion, is 

 a long diverticulum with thin walls, which runs up closely 

 adherent to the spermoviduct, ending blindly above. 



2. — Cochlicopa lubrica. — The penis is furnished with a large 

 appendix, the proximal third of which has highly muscular 

 walls; the lower two-thirds of the penis, from the origin of 

 the appendix to its junction with the oviduct, is a simple non- 

 muscular tube. The duct of the spermatheca has a small 

 copulatory branch. My results correspond with those of 

 C. M. Steenberg^and Moquin-Tandon,- except that the latter 

 does not show the copulatory branch ; they do not agree at 

 all with Ihering's figure, which is reproduced by J. W. Taylor.^ 

 I am much indebted to Mr. Charles Oldham for tridens material 

 from Berkhamsted ; the lubrica examined were from Aldenham. 



Parthenogenesis in Paludestrina jenkinsi, — The absence of male individuals 

 and of any male anatomical elements in this interesting species has been noticed 

 already {^}iivs, Journal, vol. xv (1917), p. 216 ; Trans. Herts. Nat. Hist. Soc, vol. 

 xvi (1917), p. 276). I now have evidence that parthenogenetic reproduction actually 

 occurs. In September, I9i5,a number of the snails were put in a small aquarium; 

 many were afterwards used for anatomical examination and were all found to be 

 females ; the remainder lived comfortably, and ultimately produced young ones, 

 which were first noticed in November, 1916. On ist January, 1917, three minute 

 individuals, about a millimetre long, were isolated, each in a separate jam jar, 

 with some sprigs of Elo iea from a well-searched pond which is more than two 

 miles from any known locality for jenkinsi. The jars had glass lids, and were 

 never cleaned out, nor was any fresh water or anything else put in at any time. 

 One of them was broken, and circumstances over which I had no control prevented 

 any continuous observation of the others. But I find on ist August, 1918, that 

 each contains about twenty Jenkinsi, from infants to about half-grown, and I can 

 see no way out of the conclusion that these have arisen from the single individuals 

 which were put by themselves shortly after birth. [Further progress has since 

 been made. On ist August, 1918, four more very young individuals were isolated 

 in the same way : A and B from the first parthenogenetic broods ; C and D from 

 the original aquarium. In March, 1919, all four were about full-grown, and on 

 8th April, 1919, I found a brood of young ones in B. The mother was then 

 killed and examined by a complete series of microscopical sections, without finding 

 any male organs or spermatozoa. We have, therefore, two successive partheno- 

 genetic generations. D produced a brood in May, and C in June. The parent D 

 was examined and found to be wholly female].— A. E. Boycott {Read before the 

 Society, Sept. ilth, 1918'. 



1 Dan7narks Fauna : Landsnegle, igii, p. 181, fig. 152. 



2 Histoire naturelle (1855), vol. ii, p. 306, pi. xxii., fig. 17. 



3 MonograpJi, vol. i (1900), p. 356, fig. 650. 



