THEBA CANTIANA. 19 
the true and characteristic cuwntiwna, but the anatomy of the H. dirphica, 
as shown by Herr Paul Hesse, shows divergences. 
Kickx and Van Beneden have, according to M. Colbeau, apparently con- 
fused this species with the H. carthusianella of Draparnaud. 
Diagnosis.—Theba cantiana has its greatest affinity with 7. cartu- 
siana, which in this country is always so considerably smaller that size 
alone is a sufficiently distinguishing character. 
From Hygromia striolata, with which it is sometimes confused, it differs 
in its larger and more globose form, its narrower umbilicus, more delicate 
striation, and the absence of the subearinate periphery. 
INTERNALLY, 7. cantianw is sharply separated from its congener by the 
long and filiform sarcobelum, or excitatory organ, which has now lost all 
semblance of the stylophore and accessory sac, from which it has been 
evolved, and both of which, though in outward aspect only, still exist in 
T. cartusiana. 
From H/. striolata it is at once separated by the absence of twin-darts 
and dart-sacs, which are such striking objects in that species. 
Original Description of H. carthusiana Drap. 
Animal a peu pres comme le précédent [H. carthusianella 
Drap. }. 
Coquille aussi semblable a la précédente, solide quoique 
mince, transparente, blanchatre, irrégulierement chag- 
rinée; mais elle est plus bombée et moins aplatie. On 
ne voit guere la ligne dorsale blanchatre. L’ouverture 
est semilunaire, moins allongeée et plus arrondie. L’om- 
bilic est un peu plus ouvert. Le bord columellaire est 
un bourrelet de la méme couleur au dedans, et une bande lactée au-deliors. 
Habite dans les champs. 
DRAPARNAUD, Hist. Nat. Terr. et Fluv. France, 1805, p. 102, pl. vi., f. 33. 
Fic. 112.—/H. carthus- 
tana (after Draparnaud). 
Description.—SHELL globosely depressed, rather thin and translucent, slightly 
glossy, and of a creamy-whitish colour, usually with a rufous flush on the under- 
side of the shell and on the upper side towards the aperture; the same colouring 
is also often present at the termination of the periodic growths, and renders per- 
ceptible a supra-peripheral whitish zone, while in addition 
there is a broad whitish zone margining the suture of the 
body-whorl, and perceptible only on the rufous tinted 
portions ; the SCULPTURE is composed of irregular trans- 
verse STRIZ with variably shaped malleations on the last 
whorl, while the upper whorls show a number of punctate 
depressions only perceptible under a lens, and possibly the 
vestiges of the short and somewhat recurved whitish hairs | 
present in young and adolescent shells, but which disappear In the adult. WHORLS 
6-64, convex, increasing gradually in size, spire slightly raised, suture distinct ; 
APERTURE slightly oblique, and elliptically lunate, margined externally by a narrow 
brownish-grey area, beyond which and parallel to it is a pale reddish-yellow cinc- 
ture almost two millimetres broad, which limits the duller rufous colouring char- 
acterizing the termination of the whorl. Internally, the aperture is furnished with 
a distinct white submarginal RIB, which is most prominent on the outer lip, and 
blends with the dilated COLUMELLAR MARGIN; the palatal margin is thin, slightly 
reflected, and of a rufous shade, sharply defining the white rib, which is similarly 
margined at the inner side also. UMBILICUS small and narrow, and partially 
concealed by the reflected lip. Diam., 18 mill; alt., 10 mill. Average weight of 
shell, 4:2 grains. 
Fic. 113.—//. cantiana 
Mont. (after Dupuy). 
ANIMAL with a comparatively elongate body, truncate in front, pointed and flat- 
tened behind, and the tail extending almost to the outer margin of the shell when 
crawling; dull pale brownish dorsally, becoming paler and greyer as it recedes from 
the head ; the general tint is darker at the sides, although the tubercles are more 
closely sprinkled at their apices with minute whitish specks. The whole Bopy is 
