PLATE 4. 
Fig. 1-3. Do.aBEeLLA AGASSIZI, sp. NOV. 
a 
at 
Fig. 1. Detail of the distribution of the osphradio-ctenidial nerve as seen from below; aw 
auricle; v, ventricle; c. a, crista aortae; ao, aorta; v. a, visceral artery; g. a, gastric artery; 
genital artery; p.b, dotted line indicating the boundary of the pericardium; o. B, dotted li 
cating the boundary of the organ of Bohadsch; s. b, dotted line indicating the boundary of the 
r-p. 0, Teno-pericardial opening. The parieto-visceral ganglion complex lies above the main 
trunk at the top of the figure, the left visceral ganglionic moiety lying in front of the right pa 
tion. At their left anterior ends they are joined by their respective connectives from the pleural g 
(Plate 2, fig. 1, pl-v. con, pl-par. con); v. 2, the second visceral nerve, branching at once into p. 2a 
v. 2b, which are distributed (Plate 3, fig. 2); p. 1, first parietal, or vulvar nerve; p. 2, second 
or osphradio-ctenidial nerve. The main branches of this nerve are numbered in series; 1 to 
toneum; 2 to the middorsal peritoneum and the integument forward, giving off a branch 2a, 
anastomoses with a twig from the seventh pedal nerve, 7 p. The branch 3 bifurcates into 5 and 
first passing to the anterior portion of the mantle, while the second passes to the outer face of the kidney 
giving off the branch 7 to its ventral face on the way. The main trunk, 4, now thickens decidedly ar 
gives off 8 and 9 to the venous sinus at the base of the heart and to the mantle. Numerous minu' 
short branches pass to the osphradium, osp., shown here in outline. The branch 10 ramifies t 
wall of the branchial chamber above the ctenidium, and to the walls of the branchial sinus at 
ctenidial nerve ct. n, to its tip, giving off numerous fine branches on the way. No distinct 
nor branchial ganglia other than represented in the thickened nerve-trunk itself are to be found. 
Fig. 2. Ventral view of shell. 1.7. 
Fig. 3. Detail of common genital opening. The anterior end is directed toward the | 
side of the figure; a, the integumental fold continued forward from the region of the sip 
shown at g, (Plate 6, fig. 1), along the floor of the pallial cavity and forming the dorsal 
of the genital opening. From its anterior curvature the dorsal or left ridge, J, of the genital 
extends forward, approaching its fellow, r, of the right side, which is a continuation of the incoi 
septum partially dividing the common genital opening into a dorsal and a ventral portion. XX ce 
