Farnie. — Thr Struct urt of Aniphibola crenata yiartyn. 81 



from the superior rectal sinus to the renal vein. Sections across the mantle 

 between the kidney and the rectal sinus, however, show the existence of 

 these blood-vessels. 



The rectal sinus where it traverses the roof of the mantle is very con- 

 spicuous. Quoy and Gaimard (1832) draw it as if it were coming from the 

 ventricle. Hutton (1879) says it does not come from the ventricle, as Quoy 

 and Gaimard figure ; but he was unable to trace its connection, nor does he 

 seem to have traced out the circulatory system at all. When the animal 

 is opened by cutting along the right side of the mantle the rectal sinus is 

 necessarily cut across at its hinder end where it bends upwards on to the 

 roof of the mantle. I am not c{uite certain whether the superior rectal 

 sinus ends, as shown, near the collar (fig. 3), but I can trace it no farther. 



Although the rectal sinus in Amphibola is a definite blood-vessel, I have 

 called it a " sinus " in order to compare more easily the circulatory system 

 with that of a ty])ical pulmonate — e.g., Helix. The superior rectal sinus, 

 then, evidently corresponds to the so-called rectal sinus of Helix, the 

 inferior rectal sinus being an additional vessel. The circulation of blood 

 in the lung and in the kidney agrees with that found in Helix, except that 

 in Amphibola, as in other primitive forms, the blood after being purified 

 in the kidney enters the heart directly. 



Reproductive Organs. (Figs. 3, 6.) 



Amphibola, like all the Euthyneura, is hermaphrodite. The genital 

 organs lie for the most part on the right side of the body, and comprise 

 the hermaphrodite gland (or ovotestis), albumen-gland, and an undivided 

 genital duct, into which open certain accessory organs. 



The genital aperture is situated at the base of the right tentacle (fig. 2), 

 and presumably serves for the exit of both ova and spermatozoa, though I 

 have been unable to trace the course taken by the ova in their passage to 

 the exterior. 



The ovotestis {hgl), together with the liver, occupies the visceral spire. 

 On the ventral surface it is plainly seen as a light-yellowish-brown organ 

 extending the whole length of the spire and embedded in the dark-brown 

 gastric gland. On the dorsal surface, however, only portions of the gland 

 are visible, separating the darker bands of the liver (fig. 3). It con- 

 sists of several lobules, each composed of numerous acini, the ends of 

 which are tipped with a dark-brown pigment. These lobules communicate 

 with small ductules which unite to form the hermaphrodite duct (M). 

 Posteriorly it is of a rich brown tint, but anteriorly it becomes paler till it 

 is white. This leaves the ovotestis as a very wavy duct, wdiich passes for- 

 ward on the ventral surface of the visceral spire to open into the common 

 genital duct (cd). Just before the point of entrance it gives oS a small 

 finger-shaped diverticulum, the seminal vesicle (sv), which underlies the duct 

 and rests close against the albumen-gland. 



Pelseneer (1895) in a paper discussing the origin of hermaphroditism 

 in the MoUusca refers to Aniphibola in these terms : " The wall of the genital 

 gland shows distinct sexual difterences upon the two sides of the follicles, 

 in which the female side exhibits projections which are rudiments of the 

 acini of this sex." It will be remembered that Cottrell (1911) shows that 

 in Siphonaria the peripheral acini or follicles produce only eggs, whereas the 

 central ones produce spermatozoa. In Helix each follicle produces both kinds 

 of germ cell from any part of the epithelium. My own observations tend 

 to show that Pelseneer's statement is correct, except that I do not find 



