HYALINIA NITIDULA. 69 
thick and bulky, abruptly flexed at the free end, but showing little evidence of an 
epiphallus ; the vas deferens enters nearly terminally, and the retractor is fixed 
close by; before entering the atrium the penis-sheath becomes somewhat con- 
tracted ; FREE OVIDUCT short; SPERMATHECA nearly spherical on a short duct, 
much expanded basally, and with no sign of the vaginal glands so marked in the 
preceding species ; VAGINA long and thick and terminating in a somewhat spacious 
ATRIUM or vestibule, partially encircled by glandular tissue. 
The ALIMENTARY CANAL is of the triodromous type; the GsOPHAGUs is long 
and greyish-white, darkening as it approaches the crop ; SALIVARY GLANDS white 
basally thickened, and enveloping the cesophagus ; the CROP is a broad cylindrical 
vessel, of a dirty-brown colour, tinged with purple, and merging imperceptibly into 
the STOMACH, where there is an abrupt and stiff flexure ; the INTESTINAL TUBE is 
of a dark grey, at first wide and capacious, but gradually diminishing in calibre 
after leaving the stomach ; DIGESTIVE GLAND olive-yellow, hepatic arteries whitish, 
but the main vessel is almost transparent. 
The RETRACTOR MUSCLES of Hyalinia nitens, as figured by Dr. Simroth, shows 
the PHARYNGEAL and TENTACULAR retractors as distinet and separate muscles, 
and does not show their origin from the COLUMELLAR muscle. The pharyngeal 
retractor is long and somewhat slender, slightly broadening, and becoming furcate 
for attachment to the buceal bulb; the tentacular muscles are markedly unequal 
in length, and divide quite low down, the branch to the lower tentacles being very 
long and slender, and the one to the ommatophore much stouter. 
The MANDIBLE or jaw is of the usual oxygnathous! type, about a millimetre 
wide from side to side, strongly arcuate from front to back, the whole front surface 
being delicately and more 
or less vertically striate. 
The exact shape is some- 
what variable; a specimen 
of the typical form from 
Redcar showed a_ very 
broad jaw with a bluntiy- Fic. 107.—Mandible or jaw of ‘ 
rounded rostrum or beak Ayadinia nitidula Drap. x 20. Fic. 108.—Mandible or jaw of 
and very fine vertical (Nr. Redcar, North-East Yorks., H. nttidula sub-v. helmit x 28. 
striation, while a Marske Mr. Baker Hudson). (Marske, Yorks., Mr. B. Hudson). 
specimen of the sub-var. helmii showed comparatively slender and elongate lateral 
limbs, with an acute projecting rostrum, and a greatly accentuated and protruding 
upper region. 
The ODONTOPHORE is of the usual short oblong shape, measuring about three 
mill. long, and nearly a mill. wide, and bearing thirty-five transverse rows of 
teeth, slightly converging, each row constituted by a well-developed median tooth, 
mM. A Dis ES! eet 5 é. 13. 18. 
‘S ! id A| Me WY, A Me ego 
Fic. 109.—Representative denticles from a transverse row of the odontophore of /7. uitidu/a from 
Rhoon, near Rotterdam, x 200 (after Schepmann). The formula is given as 48+8+}+38+ 4%. 
Fic. 110.—Representative denticles from a transverse row of the odoutophore of //. nitiduda X 150. 
From a preparation by Mr. J. W. Neville. 
with a largely developed mesocone and pointed ectocones, flanked by four well- 
developed and only slightly smaller lateral teeth, each bearing a large and well- 
developed mesocone and an ectocone, well marked, which, however, rapidly 
1 Monog., 1., p. 255, f. 511. 
