of Natitilus Pompilius. 67 



specimens the margin of the mantle extends over the middle of 

 the anterior surface of the pedunculated eye-ball. 



II. — Male organs of propagation of the Nautilus. 



If the mantle be reflected or removed and the Nautilus be 

 examined on the inferior surface, then it is found that the 

 animal has a space or cavity which is distinct from the visceral 

 cavity and contains the four gills. The position of the parts 

 which are visible in this gill-sac agrees on the whole in the male 

 Nautilus with that of the corresponding parts in the female. 

 The penis however does not lie, at least not exactly, on our left 

 hand, as does the aperture of the oviduct or the vulva in the 

 female*, but almost exactly in the mid-line, between the anus and 

 the funnel. This penis is of an obtusely conical form ; on the 

 dorsal surface, almost as far as its extremity, it is congruous 

 with the skin, which is distended between two large muscular 

 columns (the large shell-muscles), and by which the intestinal 

 cavity is separated from the gill-sac. On our left hand, that is 

 on the right side of the animal, is seen, between the anus and the 

 first gill, at the base of the penis, a convex swelling, which is 

 caused by a bladder lying under it. 



Let us regard, however, before further consideration of the 

 external parts, the internal organs of propagation. These con- 

 sist principally of two glands, both of remarkable size (PI. V. 

 fig. 2). If we open on the dorsal surface the sac containing the 

 viscera, then we find at the posterior end of this sac, on the left 

 of the muscular stomach, the larger of these two glands, which 

 however is in great measure concealed by the lobes of the liver, 

 and on the right side also, in some degree, by the stomach. This 

 gland, which, from the analogy of the other Cephalopods, must 

 be regarded as the testisf, is included in a thin white membrane, 

 as also the rest of the viscera are separately included in a similar 

 investment. This gland has a length of about 7 centimeters, 

 and at its broadest part a breadth of 4 centimeters ; it surpasses 

 all the rest of the viscera, the large liver alone excepted, in bulk, 

 and with its anterior margin extends as far as the heart, thus 

 occupying nearly the entire length of the visceral sac. It has a 

 flat, oval form and is bounded on the left or outer side by a 



* That is, on the right side of the auimal, which in this position turns its 

 back from us. See my fig., Trans, of the Zool. Soc. I.e. pi. 7- fig- 4. 



t In the same situation in which the testis lies in the male Nautilus, 

 the ovarium of the female is placed. Owen, indeed, says that the muscular 

 stomach at the bottom of the visceral sac lies on the left, and the ovarium 

 on the right (Memoir, p. 26, § 4) ; but this refers to the position in which 

 the animal is figured by him (pi. 5), namely lying on its back and seen 

 from the ventral surface. 



5* 



