a 
158 PUNCTUM PYGMEUM. 
spiral lineation, which is most perceptiblein the umbilical region ; APEX or nucleus 
glossy and transparent ; SUTURE distinet ; UMBILICUS wide and exposing all the 
internal spire. APERTURE obliquely lunate; Lip simple, with slightly inflected 
extremities. EEPIPHRAGM very delicate and thin. 
Diam. 1°2 mill. ; alt. 0°6 mill. 
When the animal is retracted, the ommatophores may be seen through the shell 
substance, directed towards the umbilicus. 
INTERNALLY, little is known of its structure, its minute size being a great 
hindrance to suceessful dissection. Lelimann has, however, recorded the absence 
of the dart sac and mucous glands, and deseribed the eylindrical spermatheea duct 
as short, thick, and of a biuish-grey colour; while St. Simon has deseribed the 
kidney or precordial gland as abruptly dilated behind, and the albumen eland as 
comparatively large and broad, conposed of loose tissue, and of a transparent grey. 
The JAW, according to Herr Schacko, is of 
strongly arcuate form, and nearly cirenm-oral, 
composed of nineteen quadrate plates, quite 
separate one from the other, and formed of 
long chitinous fibres which extend as a fringe 
beyond their sharp free edges ; the median plate 
is described as quite isolated, but the side plates 
overlap laterally more and more, the terminal 
plate at each extremity covering nearly two- 
thirds of the adjacent one, and all are connected 
by a delicate membrane. Dr. Pilsbry remarks : i 
that in the Nearctie form the segments are ; Mic. 21 gt 2 
not in the least soldered together, but the Rev. sa Meta Sine Gs sie) 
E. W. W. Bowell has assured me that in Britain the separate plates ultimately 
become fused. 
The LINGUAL MEMBRANE of a German specimen consists according to Schacko 
of 114 sinuous transverse rows, each composed of thirty-nine distinctly isolated 
teeth, even the cutting points or cusps not reaching to or overhanging the basal 
surface of the adjacent rows. The transverse rows are each composed of a long and 
narrow median tooth, with a tricuspidate reflection, although the side-cusps are 
occasionally so sinall as to be seareely perceptible ; the laterals are double the width 
of the central tooth, and bicuspid, with rounded eutting points, merging gradually 
into the less delinite marginal teeth. The formula is 19+1+19 x 114=4,446 teeth. 
call 
2 
er 
Fic. 216.—Transverse row of teeth from the odontophore of Punctum pygmteum (Drap.), Cambridge, 
highly magnified, prepared by Prof. H. M. Gwatkin. 
A British specimen showed a well-delined, though slender, trifid median tooth, 
flanked by many practieally bicuspidate laterals, with simply hooked reflections, 
which gradually blend with the obscurely tricuspid marginals. 
The formula of a Canibridge specimen of P. pygmewmn, prepared by Prof. 
Gwatkin, is 4+44+4+14+4x48=1,776, but the preparation may be imperfect, as 
Prof. Gwatkin quotes sixty-five transverse rows as present in a Tenby specimen. 
Reproduction and Development.— Nothing is known of the details 
of the congress of this species, but Gassies records that usually during 
August and September about a score of very small and opaline eggs are 
deposited, which hatch in due course, the young becoming adult near the 
end of the following year. 
Habits and Habitat.—'I'his species would seem to have little 
geological preference, being found equally on limestone and sandstone 
soils, living chiefly in moist and shady places within or at the margins of 
woods, hiding beneath stones, at the roots of grass, or amongst moss, 
principally favouring //ypnrum purun and FH. lutescens, but is also very 
