Rodentia. — The Weberian organ showed mama, and Hypudous amphibius, I have looked for it in vain. But certainly the illy ants Mims dEgyptiacus and Cricetus vulgaris exhibited a single small longitudinally folded verumontanum, which, from its situa tion between the two orifices of the vasa de ferentia, must have been the opening of a Weberian organ : but this structure iself, on account of its sheer minuteness and hidden situation, eluded the further searches, which were made in only a few individuals.
In Curia cobaya the Weberian organ is, as I described it some time since*, a small roundish vesicle, scarcely a line in size, which has a bilobed extremity, and, as in Macro seelides, a constricted neck, which opens into the uro-genital canal between the two seminal ducts. The Weberian organ of the rabbit and hare is very much larger. It was formerly known to the older zootomists under the name of the azygous seminal vesielet, and has only received a more accurate description and ex great variations in occurrence, size, and shape. In Sciurus vulgaris, 7ainies striate*, phihts Willi's, in Ales mesculus and dem planation through the researches of Httschke and Weber.
In the rabbit this organ attains a length of from one to one and a half inches, so that it projects very far,lichind the urinary bladder. It has the form of a flask, and in its anterior half, which is compressed somewhat flat, it has a breadth of five to six lines. Its base is bi lobed, as if drawn out into two lateral short and rounded horns. Its mouth in the uro genital canal is wide (about one line), yet not round or linear, but rather placed across, and somewhat arched in shape, as if bent around the swelling of the verumontanum. In new born individuals the organ is much smaller, scarcely three lines long; but it is otherwise txactly similar. In the male hare it is al ways smaller. In one example it measured five lines, and was devoid of horns at the base ; but these are sometimes little developed in the rabbit also. But the most extraordi nary circumstance about the utriculus of these animals is this, that it receives the ejaculatory ducts. In all other instances, these open in dependently, by its sides, into the uro-genital canal ; but here, departing from this rule, they open into the undermost part of the Weberian organ, at a short distance (in the new-born rabbit half a line, in the adult two lines) above its orifice previously described.
They occupy the anterior wall of the organ, on which they course downwards, and each terminates in a small papilla. In Lagonds the same arrangement seems to occur. At least Pallas* states of the Lagontis ogstona that the two ejaculatory ducts open together by a common tube, which must doubtless be regarded as a Weberian organ. Another very remarkable form of Weberian organ is possessed by the beaver. The first intbrination concerning it we owe to Brandt and Ratzeburg$, who compared this struc ture, on account of its form, to the uterus bicornis of the female individual, yet without recognising any nearer relation between the two. They regarded it as a kind of sup plementary' seminal vesicle. Its correct inter pretation is due to the acuteness of Weber.§ The Weberian organ is simple only at its lower end, or that which usually opens be tween the orifices of the two vase deferentia. Very soon it is split into two horns, which ascend in the peritoneal fold between the two seminal ducts, and finally, after they have dwindled to the form of threads, are apposed to these. Brandt and Ratzeburg were able to follow the terminal threads to the testicles; while in the example which Weber inves tigated, where the horns measured 2/ inches, they ceased much earlier. The lower half of the horn is of very considerable thickness, as much as four lines, and it encloses a spacious cavity.
Edenlata.— The sloth (Brarlypus friday tylus), the only animal of this class of Main rnalia whose genitals I was able to examine, is completely devoid of this organ.
Pachydermata.— Duvernoy # mentions the Weberian organ in the elephant as a deep, blind sac, which lay concealed in the veruT montanum. In the swine it has been de scribed by Weber. It consists here of a body, which is nine lines in length and almost a line in thickness, and which lies in the peritoneal fold between the two ejaculatory ducts. At its tipper end it passes on either side into a 3 et longer but thinner horn. Leydig, who also mentions the opening of this body into the uro-genital canal, states that, when in the inflated condition, it has the thickness t.f a goose quill.