.ON THE PAIRED NEPHRIDIA OF PROSOBRANCHS. 601 
T can also account for Bela Haller’s statements on the 
point at issue. The funnel he describes is nothing but the 
section of the aorta (compare his pl. i, fig. 1, with my own 
fig. 3, and Boutan’s [2] pl. xxiii, fig. 6). The renal end of his 
reno-pericardiac duct is nothing else than the genital duct 
(compare my fig. 18 with his fig. 2, pl. i). The same anato- 
mist describes an entirely imaginary genital duct, which is 
only the inferior right mantle nook shown in my fig.6. Had 
Haller carefully studied unbroken series of sections (he 
figures sections, but has probably not been able to cut com- 
plete series) he would certainly have avoided these mistakes. 
Perrier certainly directed his attention almost entirely to 
the left kidney, rather neglecting the point whether a right 
reno-pericardiac duct really existed. The canal which he 
figures would be quite satisfactory were the opening into the 
kidney to be seen, which is not the case. He was evidently 
misled by Haller and by misunderstanding v. Jhering, who 
says that he could not satisfy himself as to the presence of a 
right reno-pericardiac duct. The latter information was 
obtained from Perrier’s answer to my letter. 
Emarginula Houzardi.—The anatomy of this species, 
as seen after the removal of the shell through the very thin 
mouth, is illustrated in fig. 11. It closely resembles that of 
Fissurella. The right kidney, however, seems to be some- 
what smaller than in Fissurella. 
Fig. 27 is a perfectly transverse section through the peri- 
cardium and both kidneys of Emarginula. The external 
opening of the left kidney (X/) is very plainly seen in the 
section. 
Puncturella spec.?—The same remarks I made about 
Emarginula can be applied to Punctureilla. 
Fig. 15 shows a transverse section through the pericardium 
and both kidneys of this species, which is certainly more 
primitive than Fissurella and Emarginula, as the visceral 
hump (fig. 22, H.) is much better developed here. 
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