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Show 118 MR. R. H. BURNE ON [Feb. 19, of the two lobes into which the gland is divisible. After a short course free of the gland-substance, the ducts are said to open into a spindle-shaped muscular reservoir, from the anterior extremity of which a single duct (Wharton's duct) leads to an opening in the floor of the mouth beneath the tongue. This description is only partially true, for, of the two main collecting-ducts, one only (i. e. that coming from the larger and most posteriorly situated lobe of the gland) opens into the muscular reservoir and continues from its anterior extremity to the opening beneath the tongue ; the other, although it enters the wall of the reservoir, has no communication with its cavity, but courses down its dorsal margin close beneath the lining epithelium and continues as a separate duct, intimately connected with the first, to an opening beneath the tongue. (It was not seen whether these two ducts opened into the mouth by a common aperture or separately.) A n arrangement of the submaxillary glaud and ducts precisely similar to this was found in Dasypus sexcinctus (text-fig. 18), but, owing to the greater size of the creature, the individuality of the ducts was more easily seen. Somewhat similar features were also observed in the Three-toed Sloth (Bradypus tridactylus, text-fig. 19). The submaxillary gland in this animal is divisible, as in the above-mentioned Dasypodidae, into two well-marked lobes each provided with its own duct. The two ducts run side by side (with, however, no muscular reservoir on either of them) to the floor of the mouth beneath the tongue. The duct from the smaller and more anteriorly situated lobe of the gland is remarkable for its large calibre and for the thinness of its walls-in fact at first sight it had very much the appearance of a vein. The duct from the larger and posterior lobe was double throughout its length on the right side, but single on the left. The meaning of the conditions observed in the submaxillary glands and ducts of these three Edentates becomes, I think, clear on reference to a paper by Eanvier1, in which, in addition to numerous observations of his own, he collects and harmonizes the previously confused statements concerning the relations that subsist between the sublingual and submaxillary glands. It is well known that frequently in M an there occurs a large duct (duct of Bartholini) that arises from a posterior portion of the sublingual gland and runs alongside Wharton's duct to open with it or near it under the tongue. Bartholini himself 2 described and figured a similar duct in the Lioness, having its gland in close connection with the submaxillary, and Eanvier adds a large number of mammals in which the same gland (called by him Eetro-lingual) is found with great constancy. According to Eanvier the retro-lingual gland lies always posterior to the lingual nerve, and for this reason (a somewhat arbitrary one it 1 Ranvier: " Etudes anatomiques des Glandes connues sous les noms de sous-maxillaire et sublinguale, chez les Mammiferes." Arch, de Physiol, xviii. 1886, p. 223. 2 Bartholini: D e ductu salivali hactenusnon descripto observatio anatomica, 1685. |