250 Conchological Classification, Variation & Nomenclature. 



respects from Hyalinia cellaria and its close allies, which I have 

 classified as Etihyalinia, but which Kennard and Woodward 

 propose to unite with Polita. 



The group Polita, as represented by P. nitidula, has a shell 

 with a comparatively dull and waxen aspect, usually somewhat 

 loosely coiled and more widely umbilicated, while Euhyalinia 

 has typically a brilliantly glossy shell, usually more compactly 

 coiled and with a more contracted umbilicus. 



The animal inhabitant also presents more or less constant 

 differences ; in Euhyalinia the lateral furrow on the right side 

 of the body is distinctly present, whereas in Polita this groove 

 (which is probably a vestige of the formerly external spermatic 

 channel of the ancestral form) is not perceptible, and in addition 

 there are differences in the character of the pallial lobulation 

 in the species of the two groups. 



Internally the differences between Polita and Euhyalinia 

 are even more decisive and entirely preclude the feasibility of 

 the union which Kennard and Woodward propose. 



In Euhyalinia the sexual system shows a well developed 

 glandular pad, which envelops the upper part of the vagina 

 and represents the digitate glands of Helix ; there is also a 

 remarkable and peculiarly looped epiphallial expansion of the 

 vas deferens and the penis is innervated from the right cerebral 

 ganglion; while in Polita the two first characters are quite 

 deficient and the penis is stated to receive its innervation from 

 the pedal ganglia. 



In Euhyalinia also, the retractor of the right ommatophor 

 passes between and separates the male and female organs of 

 the sexual system as in the typical Helices, whereas in Polita 

 as properly restricted, the retractor is quite free from the 

 sexual complex as in the Xerophiloid Helices. 



In Euhyalinia too, the median teeth of the radula are smaller, 

 and in some cases conspicuously smaller than the neighbouring 

 laterals, which are usually tricuspid in plan, while the marginal 

 teeth are typically few in number ; whereas in Polita the 

 median teeth are quite as large as the adjacent laterals, which 

 in this group are usually bicuspidate, while the aculeate mar- 

 ginals are more numerous. 



Nomenclature. — Kennard and Woodward (Post Pliocene 

 Non-Marine Mollusca of Ireland, 1918, p. iii, et seq.) are quite 

 ruthless in their condemnation of Varietal nomenclature as 

 adopted by those who are striving to study intensively the 

 range of variation in the various species of mollusca, and need 

 a full and accurate nomenclature adapted to their requirements. 

 Messrs. Kennard and Woodward, however, chng to ancient 

 methods, which though ample enough for the modest require- 

 ments of science in former times, or for the general student of 

 the present day, are quite out of harmony with the minutely 



Naturalist, 



