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Show 366 DR. H. GADOW ON THE SYSTEMATIC [May 3, the anus : this is probably a character adapted to the fossorial habits of the creature, a parallel case being afforded by Perameles. It would be rash to infer from this similarity any special affinity between these two genera. IV. The teeth are built after the zoophagous marsupial plan; it is, however, significant that the crowns of the teeth of the Dasyuridce, and especially those of Myrmecobius, show the same type of structure as those of Ornithorhynchus (cf. Poulton and Leche *). The teeth are present in considerable numbers, and, with the exception of a few, remain functional throughout life. There is no indication whatever of their becoming superseded by a horny covering of the jaws, the naso-frontal horny shield of Notoryctes being a special feature which has no resemblance to, or connexion with, the covering of the jaws of the Monotremata. The determination of the full number of teeth was wisely left in abeyance by Prof. Stirling, although he suggested the following formula: i. |, c. y, p. |, m. | = ~. The material placed in m y hands before the specimens were distributed to their ultimate places of destination has enabled me to arrive at some interesting results. For future reference and possibility of identification I append the following list, the numbers being those which Prof. Stirling had enclosed in the various bottles :- Specimen A.-Refers to the specimen figured by Stirling on plate vi. of his monograph. Preparation of skull, in spirit. Cambridge Museum. Specimen B.-Dry skull and skeleton. Cambridge Museum. Specimen C . - A partly dissected specimen. Roy. Coll. Surg., London. Male I.-Spirit specimen. Nat. Hist. Mus., S. Kensington. Male II. „ „ Roy. Coll. Surg., London. Male V. „ „ Cambridge. Female I.-Spirit specimen. N. H . Mus., S. Kensington. Female III. „ „ Stockholm Zootom. Inst. Female IV. „ „ Cambridge. The full nmnber of teeth seems to be: i.-, c. j, pm. ^ m« 4=KT Probably the two upper and the two lower premolars represent the original pm. 1 and pm. 3, it being supposed that, as in Dasyuridce and some other Marsupials, the original pm. 2 and 4 have been lost. Pm. 3 is fully developed and bicuspid in both mandibles of specimens A and B, and in the right mandible of female I. Pm. 3 is reduced to a very small, short, and pointed tooth on both sides in male II., left side of female IV., and right side of specimen C. Pm. 3 is absent on both sides in male I., male V., female III.; right side of female IV.; left side of specimen C. 1 Poulton, Quart. Journ. Microsc. Sci. 1888. W. Leche, ' Biologiska Fore-ningens Forhandlingar,' Stockholm, 1891, iii. no. 17, pp. 136-154: " Beitrage zur Auatomie des Myrmecobius fasciatus." |