HYGROMIA REVELATA. 39 
RETRACTOR MUSCLE is attached to the epiphallus; VAS DEFERENS slender, but 
thickened at its junction with the penis-sheath. When immature the dart-sacs are 
Fic. 49. Fic. 50. Fic. 52. 
Fic. 49.—Proximal part of Alimentary system of Hygvomia revelata, from Guernsey, collected 
by Mr. J. R. le B. Tomlin, showing position and character of salivary glands and their ducts. 
6. buccal bulb; cv. crop; s.g. salivary glands. 
Fic. 50.—Reproductive system of Hygromia revelata, from Guernsey. 
a.g. albumen gland; d.s. vestigial stylophores and accessory sacs; /7. flagellum ; #.g7. mucus 
glands ; o¢. ovotestis ; ov. oviduct ; ef. epiphallus; #. penis-sheath; 7. penial retractor ; s.d. sperm 
duct or prostate; wv. vagina. 
Fic. 51.—Enlargement of distal part of vagina, mucus glands and dart sacs of Hygromia revelata 
from Guernsey, to more clearly show their peculiarities. 
Fic. 52.—Penis-sheath and its accessories of Hygromia revelata, from Guernsey. 
fi. flagellum ; Z.s. penis-sheath ; v.d. vas deferens. 
scarcely perceptible, and the mucus-glands are shorter. 
The JAW or mandible is about three-fourths of a millimetre in width; narrow, 
slightly arcuate, thin, of a fawn or amber colour, 
except along the cutting edge and the thickened trans- 
verse ribs, which are of a blackish brown; there are 
about twelve fairly distinct transverse or vertical ribs, 
which extend across the anterior surface, and denticu- 
late the upper and lower margins, and in the specimen 
examined appear to be arranged in three groups of Fic. 53.—Jaw of H. revelata 
about four ribs each, the central group forming an from Penzance, x30, from micro- 
obscurely defined median projection. photo. by Mr. W. Bagshaw. 
The RADULA is of the usual type, and about 14 millimetres long and _ three- 
fourths of a millimetre wide, with about 92 sinuately transverse rows of teeth, with 
a maximum of about 39 teeth in a row, each row being composed of a symmetrical 
tricuspidate somewhat quadrate median tooth, bearing a stout median cutting point 
or mesocone and two distinct side cusps or ectocones ; this central tooth is flanked 
on each side by about twelve laterals, which are unequally bifid, the endocone being 
suppressed ; the marginals or outer teeth are the outer series, and are usually 
about seven in number at each side, they are tridentate in plan, the endocone 
becoming prominent as an obliquely projecting cutting point; as the margin is 
more closely approached the ectocone may be duplicate, and the teeth become 
quadrifid, before reverting to the simple unicuspid type of the outermost row. 
“Wold Sally) hy 
Fic. 54.—Representative teeth from the radula of Hygromia revelata, Penzance, Cornwall, 
from a highly-magnified micro-photograph by Mr. W. Bagshaw. 
The formula of a specimen from Guernsey collected by Mr. Tomlin is 
sat + ote + sic x 92 = 3,588 teeth. 
