a 
136 ZONITOIDES EXCAVATUS. 
The LINGUAL MEMBRANE is of the usual oblong shape, and somewhat recalls 
that of Hyalinia nitidula, but has nine bifid laterals instead of fonr, as in that 
species. It still more closely resembles that of its close ally Zenitoides nitidus, but 
the teeth are rather narrower. 
The radula bears about eighty obliquely curved rows of teeth, each row com- 
posed of a rather broad median tricuspid tooth ; the mesocone and ectocones being 
sturdy and strong ; the bifid laterals show a very broad and strong mesocone, with 
a well-developed and conical ectocone, while the marginals are of the simple 
aculeate pattern. 
The formula of the species is usually 1° +$+}+3+1° x 80=4,080. 
9. 
17. 1%. 10. MMS: BA ee ee Nas LY m. 
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Fic. 188.—Representative denticles from a transverse row of the teeth of Zonzttoides excavatus (Bean), 
from England, supplied by Dr. Jeffreys, x 600 (after Schepmann), 
Reproduction and Development.—No details are known of the 
congress of this species, but the act evidently takes place early in the 
year, as loosely agglutinated clusters of four to six slightly ovate eggs 
have been found in the beginning of March, while adults have been found 
often contaiing darts as late as the middle of May, but after that period 
darts were absent from mature specimens, which became more uncommon 
and the iets specimens more plentiful. 
Food and Habits.—/onitoides excavatus is a local and sometimes an 
abundant species, often living in company with Helix rotundata. It is a 
species with no especial predilection for a limestone soil, while im the 
north of England it is most plentiful on the Coal Measures. It hides 
beneath dead and decaying leaves and fallen timber in woods or hedge- 
rows, and though a truly geophilous species, has been observed climbing 
the stems of “Bracken” (Pteris aquilina) and even living among /ris in 
moist hollows in company with Z. nitidus. 
Though often found abroad on the milder days of winter, it buries itself 
during the more severe weather six or eight inches deep within the fibrous 
earth below the layer of dead leaves, forming a delicate epiphragm. 
Mr. F. Taylor has remarked on its predilection in Lancashire for the 
runs of field mice, and believes they feed upon the mice droppings. 
In Ireland, Mr. R. Welch has observed that it is rarer in Kerry on the 
Carboniferous Limestone than on the Old Red Sandstone, and that its 
habitat is almost invariably in or on the margins of the ancient woods, 
or in the damp little glens, mostly near the coast, with their old native 
serub, often the only remnant in a district of the primitive forests of 
Ireland, destroyed since Elizabethan times when the country was largely 
forest. It is never found in new woods or in cultivated areas unless they 
adjoi some old rough ground or primitive woodland. 
Geological Distribution.— PLEIstocenr.— Recorded by Prof. Rt. 'Fate 
as found fossilized in the freshwater marls of Copford, Clacton, ete., in 
North Essex. 
In Kast Suffolk, it is recorded by Prof. Morris from the freshwater 
deposits of Stutton, on the authority of Mr. Searles V. Wood. 
Horocenr.—Found by Mr. R. M. Christy in the deposits by the river 
Cann, at Olea St. James, in North Essex. 
