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Show 1887.] ANATOMY OF HYDROMYS. 61 lobes, the supernumerary pair being placed behind and below the others. Alimentary Canal and Appendages. Teeth.-The dentition is as described by Owen1, I. \, M . \, the total number thus being smaller than that of any other Rodent. The incisors closely resemble those of the Common Rat. The upper incisors are stouter and shorter than the lower; they are set closely together, their edges meeting at their inner angles, so as Fig. 3. Left hand of Hydromys chrysogaster. (Natural size.) Fig. 4. Left foot of Hydromys chrysogaster. (Natural size.) Fig. 5. Upper and lower incisors of Hydromys chrysogaster: a, intermandibular muscle; b, tongue. to enclose a wide angle (vide fig. 5). The portion projecting beyond the alveolus is 1*05 cm. in length. The first upper molar is a large tooth, consisting of two segments of nearly equal size and a third of lesser magnitude (vide fig. 6, b and c). It possesses three large fangs, one at either extremity and the third at the middle and on the lingual edge. At the opposite side of the tooth to this last are three i ' Odontography,' vol. i. p. 410, and Comp. Anat. of Vert. vol. iii. p. 300. |
