1906-7.] Helix pomatia with Paired Male Organs. 
331 
Y.D. Vas deferens. 
Y.D.S. Supernumerary vas deferens. 
Y.P.G. Viscero-pleural ganglion. 
Y.S. Yesicula seminalis. 
+ In fig. 1 indicates the position of the epidermal blind end of the supernumerary 
vas deferens. 
Figures* of the Abnormal Specimen of Helix pomatia, L., 
ALL TWICE NATURAL SIZE. 
Fig. 1. The anterior end seen from the left side, to show the supernumerary 
genital orifice (G.O.S.). The + marks the position of the epidermal blind end of 
the vas deferens. For further description, see pp. 315, 316. 
Fig. 2. The dissection seen from the dorsal aspect. The alimentary canal, 
heart, nephridium, and roof of mantle chamber have been removed and the repro- 
ductive organs spread out so as to display the various parts. The supernumerary 
flagellum (Fl.S.) is incomplete, its terminal portion having been accidentally severed 
and lost. The cerebral ganglia (C.G.) are shown still enclosed in their sheath (as the 
latter could not be safely removed), as are also the connectives (Cn.). The sheath 
has, however, been removed from the viscero-pleural ganglion (Y.P.G.), which is seen 
to be divisible into five portions — a median abdominal ganglion, right and left of 
which is a visceral ganglion, to the outer side of each of which is a pleural ganglion. 
The pedal ganglia are more ventrally situated and are not shown in the figure ; 
only a few of the pedal nerves are shown ; no attempt has been made to represent 
those which run posteriorly. On the right side the muscle (M.Retr.) which retracts 
the anterior end and the foot has been severed ; the retractor of the buccal mass 
(M.Retr. B.) has also been cut through. 
For descriptions of the normal and supernumerary reproductive organs, see 
pp. 312, 313, and 314, 315. 
Fig. 3. A dissection of the supernumerary organs from the left or outer aspect. 
The outer and inner sheaths of the penis have been cut open to show the copulatory 
organ (C.O.), the introvert (Intr.), and also the rugose folds on the inner surface of 
the inner sheath. The blind end of the vas deferens (V. D.) is seen close beneath 
the epidermis, to which it is attached by a short cord of connective tissue (Con.T.). 
Only a small portion of the flagellum (Fl.S.) is shown. A bristle has been passed 
through the external genital opening into the lumen of the penis. For further 
description, see p. 316. 
Fig. 4. A further dissection of the distal portion of the penis, from the left or 
outer aspect. The incision in the sheaths of the penis shown in fig. 3 has been 
continued to the left (that is, distally), so as to extend to the genital opening. The 
flaps have been turned back so as to afford a clear view of the inner surface of the 
inner sheath in its distal portion. Note the longitudinal folds and the papilla 
(Pa.). Probably the region from this papilla to the external opening (G.O.S.) 
ought to he regarded as atrium. For further description, see pp. 316, 317. 
* The cost of drawing the figures on stone has been defrayed by a grant from 
the Carnegie Trust for the Universities of Scotland. 
( Issued separately October 4, 1907.) 
