WYALINIA HELVETICA, 47 
he continental specimen of //. helvetica examined by Mr. Woodward 
shows forty-five transverse and thirty-live longitudinal rows of teeth on the 
radula, agreeing in the latter respect with Herr Schepmaun’s observations, 
and in this point a tendency is undoubtedly shown by the species gener- 
MG LALA ale 
Fic. 76. Fic. 77. 
Fic. 76.—Representative denticles from half a transverse row of the odontophore of a topotype of 
Hyatlinia helvetica (Blum), from Solothurn, x 200 (after Schepmann). 
Fic. 77.—Mid and admedian teeth of //yadinia helvetica (Blum), from Folkestone, collected by Mrs. 
Fitzgerald, x 200 (after Schepmann). 
ally towards an increase in the number of marginals, and though Signor 
Pollonera has satisfactorily established that this feature is. due to the 
increasing age of the animal, yet the examples inhabiting Central Europe 
would appear to have advanced a step further and reached a point of 
ereater equilibrium in this respect than those of our own country, thus 
again enforeing the truth of the principles of evolution and geographical 
distribution propounded in the present work.’ 
Diagnosis.—The suet of //. helvetica may be separated from that 
of its close ally, //. alliaria, by its larger size, its more convex and swollen 
outline above, and its greater flatness beneath; the umbilicus also is 
comparatively and actually narrower, and the surrounding opaque whitish 
area more pronounced, 
From /Z. celluria it may be distinguished by its smaller size and greater 
proportionate height, its rounder mouth, its less perceptible basal opacity, 
and by the umbilicus not disclosing the penultimate whorl so fully as m 
IT. cellaria. 
he ANIMAL is distinguished from that of //. alliaria by its paler 
colouring, the much more distinet zebra-like markings of the body, and 
the deep-black edging to the mantle, which shows as a broad and sharply- 
defined black line near to and parallel with the mouth of the shell whether 
the animal be in motion or retracted and at rest within. In crawling, the 
tail extends considerably beyond the shell. 
From //. cellaria it differs strikingly by the distinct zebra-like transverse 
striping along the sides of the body, and by the peculiar broad and black 
wmantle margin. 
InrerNALLy, the white arterial network overspreading the surface of the 
liver or digestive gland is a characteristic feature, in which it resembles 
Zonitoides excavata and also Arion ater, while the radula often shows a 
weaker development of the mesocone of the median teeth, resembling in 
this respect the true //. glabra. 
Description.—ANIMAL with a bluish-grey Bopy, darkest towards the head, but 
showing whitish-grey by transmitted light; faintly darker zebra-like transverse 
stripes are distinetly perceptible on the sides of the BODY, arising at the DORSAL 
GROOVES and terminating at the lateral lines, below which the colouring is paler 
and the tuberculation less crowded ; MANTLE quite dusky, its outer margin sharply 
defined by the characteristic broad black line ; FOOT-SOLE long and narrow, about 
15 mill. long and nearly 2 mill. wide when crawling, of a yellowish-grey colour, but 
in some specimens when the animal is contracted the dise appears quite yellow ; 
TENTACLES about 4 mill. long, somewhat slender and granulated, of a dark-grey or 
1 Monog. i., p. 385 to 403 and pls. iii., iv., and vi, 
