THE NAUTILUS. 135 
Heliz hortensis. The one I take as typical of the variety meas- 
ures 16 by 20 mm., and the apex, with curved rows of granules, 
is delicately tinted with orange, giving the shell a more recent 
appearance than usual. This may be the latest phase of bow- 
ditchiana, but its resemblance in form to more ordinary snails 
might be taken to indicate greater antiquity. I was not able to 
make out distinct zones in the Porto Santo fossil beds, although 
some species abound in one place, and are rare or absent else- 
where. The sandy deposits are broken down by the weather, 
and the shells loosened upon the surface. Many of these are 
again covered, as the wind blows the sand, and the lime again 
cements the deposit, so that it is quite possible to find shells of 
entirely different ages mixed together. In fact the very modern 
H. pisana is being thus incorporated, and no doubt in years to 
come it will be possible to dig pisana and bowditchiana out of 
the same fossil-beds, just as if they had been strictly contem- 
poraneous. 
In order to show the greater uniformity in the Canigal P. 
bowditchiana, I give the measurements of 156 shells, citing the 
two dimensions as before. 18.19 (1), 18.21 (1), 19.20 (2), 
19.21 (7), 20.20 (6), 20.21 (18), 20.22 (8), 21.21 (9), 21.22 
(22), 21.23 (7), 21.24 (8), 22.21 (1), 22.22 (12), 22.23 (28), 
22.24 (2), 23.22 (1), 23.23 (5), 23.24 (13), 23.25 (1), 24.22 
(1), 24.24 (2), 24.25 (4), 26.25 (1). 
The nearest living relative of P. bowditchiana is P. punctulata 
(Sowerby), exceedingly common on Porto Santo, and found 
also on the outlying islets, even the isolated Ilheo de Nordeste. 
It hides under rocks, more or less buried in the ground, and I 
never saw it crawling abroad. A remarkable feature is the 
opaque white mantle, which, when the animal is within the 
shell, looks at first sight like a dense white epiphragm. The 
genitalia show a very long slender flagellum. The living ani- 
mal may be described as follows: Animal whitish translucent ; 
tentacles and neck above dark grey, nearly black; foot very 
broad, caudal end very broad and flat; a large black mark on 
each side posterior to tentacles; mantle opaque white (speci- 
men from Villa Baleira). The shells vary much in color, some 
being very dark. Two bands, never seen in bowditchiana, are 
