JOURNAL OF CONCHOLOGY. 1 67 



the whole of the eggs between this slug and the pair that fer- 

 tilised each other. In the former case it was 172 days, in the 

 latter only 48 days — being a difference of 124 days. 



So far I have not been able to find any writings touching 

 on self-fertilization in hermaphrodite gasteropods, and the point 

 is well worth further experiment, in the course of which the 

 ovatestis should be examined to see if it produces ova and 

 sperms at the same time, or whether the latter are stored up in 

 the seminal receptacle before the ova ripen. Unfortunately I 

 was unable to prosecute my investigations any further then, and 

 I have not been able to devote the amount of time such a pro- 

 ceeding requires since. 



For the purpose of shewing the development of the slug 

 within the egg, I prepared for sectioning six eggs on the day of 

 exclusion, and six eggs each succeeding day until the slug was 

 fully formed. This I hope to make the subject of a future 

 paper. 



Cardiff, October ijth, i8g2. 



Pisidia near Leicester. — The simultaneous occurrence 

 of all the British species of the genus Pisidium is perhaps un- 

 usual enough to be worth recording. When at Aylestone, near 

 Leicester, last July, I found the following forms within a space 

 of five or six j'ards, in the Union Canal^ near its junction with 

 the river Soar : — P. amnicum, P. fontinale and v. hen slow an a, 

 P. pusilliim, P. nitiduviv. globosa, and P. milium. P. fontinale 

 V. henslowana and P. pusillum were very abundant ; the others 

 occurring more sparingly. P. milium and P. nitidum are addi- 

 tions to Mr. Quilter's ' List of Leicestershire Shells ' (Trans. 

 Leices. Lit. and Phil. Soc, 1888) as is Bythinia leachii, which 

 I took in the canal at the same spot. — Charles Oldham, 

 Ashton-on-Mersey, Oct. /j", i8g2. (Read before the Concho- 

 logical Society, y^^. 11, iSgj). 



