JOURNAL OF CONCHOLOGY. 369 



On making a comparison with the gonads of the Helices 

 and those of the Limnsese, it will be found that the greatest 

 dissimilarity of the latter from the former occurs in the great 

 separation of the male and female portions from one another, 

 this being a decided advance on to the monoecious condition ; 

 the presence of the large and well-defined prostata, the existence 

 of the so-called accessory albuminiparous glands, and the absence 

 of muciparous glands, dart-sac and flagellum. The absence of 

 the dart in other species than those of the Helicidse suggests not 

 the idea (I may incidentally mention) that my friend Prof J. 

 Bland Sutton has recently proposed to me as an organ of cuti- 

 cular irritation, an idea which I find is held by Simroth in a 

 paper entitled " Ueber eine Nacktschnecke von Samarkand die 

 Amalia maculata, Heynemann^ besser Agriolimax maculatus," 

 which he communicated to SB. Ges. Leipzig, xii„ pp. 11 and 12 ; 

 hut rather inclines to the theory proposed by Mr. W. E. CoUinge, 

 in a paper on " The Darts of the Helicidae," read before the 

 Leeds Naturalists' Club and Scientific Association, on October 

 29th, 1887, viz., that it must be considered as a degenerate 

 weapon of defence. But I would point out that the only basis 

 on which we must build the most probable function of the dart 

 must be one founded on inferences derived from embryological 

 considerations which. are not, as yet, forthcoming. 



Limnaeaauricularia floating. — It will doubtless interest 

 Mr. Nelson and others (vide 'A Day's Collecting near Howden, 

 York.s.,' pp. 262— -267 ante) to know that I observed this 

 afternoon (May 7th) a distinctly marked auricularia floating on 

 the surface of the water in a large pan wherein I am keeping a 

 quantity of specimens alive for anatomical work. These 

 specimens were taken yesterday afternoon by Mr. Wallis Kew 

 and myself from the Lea Marshes, Tottenham, and were only 

 placed in the water in the early morning of to-day. — J. W. 

 Williams. 



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