312 DA8TTrEIDJ3. 



that the tooth is distinctly tricuspid. Molars small and delicate, the 

 middle ones of the series the largest ; m.' very small and narrow, its 

 edge indistinctly serrate ; m.', m.', and m.* triangular or oval, very 

 variable in size and shape, generally with from three to five small 

 pointed cusps ; m.° smaller than the others, generally similar to 

 them in character, but sometimes minute and styliform. 



Lower teeth very like the upper. Incisors slender, i.' markedly 

 the largest. Canine proportionally larger than in the upper jaw. 

 Premolars almost precisely like the upper ones, but the anterior 

 secondary cusp less developed. First molar very small, but variable 

 in size, sometimes minute and unicuspid, generally bi- or tricuspid, 

 but sometimes still larger and quadricuspid. Other molars each 

 with three marked subequal internal cusps, but with the outer row 

 of cusps suppressed and reduced to a mere roughened cingulum, 

 which is carried on backwards behind the last internal main cusp, 

 and forms a low extra posterior cusp or heel. 



Milk-premolar as yet unknown, the determination of the pre- 

 molars and molars depending upon form and upon the relative times 

 of appearance of the different teeth. 



EabiU. Terrestrial and arboreal ; insectivorous. 



Range. That of the only species. 



This exceedingly remarkable genus differs from all the rest of the 

 family to such a degree that it is very doubtful if a special family 

 ought not to be made for it. Its chief interest lies in its close 

 resemblance and, presumably, relationship to the Mesozoic Polypro- 

 todont Marsupials of the English Jurassic beds, the resemblance 

 being so close as to suggest that Myrmeedbius, like Oeratodus, is 

 actually an unmodified survivor from Mesozoic times, and therefore 

 from a time long before the Didelphyidai, Peramelidce, and Dasy- 

 uridcB were differentiated one from the other. As to its family 

 distinction, however, it seems better for the present to retain aU the 

 simple-footed predaceous Marsupials in one large family, with which 

 further discoveries will probably show that the Am/pMiheriidm and 

 their allies should be amalgamated, rather than to split up the living 

 forms in such a way as to increase the difiB.culty of assigning their 

 proper family positions to the fossil ones. 



1. Myrmecohins fasciatns. 



Myrmecobius fasciatus, Waterh. P. Z. 8. 1830, pp. 69, 131 ; id. Cat. 

 Mamm. Mm. Zool. Soc. p. 65 (1838); Gerv. C. H. vii. p. 672 

 (1838; ; Owen, P. Z. S. 1838, p. 121 ; Waterh. Tr. Z. S. ii. p. 149, 

 pis. xivii. (animal), xxviii. (skull &c.)(1841) ; id. Jard. Nat. Libr., 

 Mamm. xi. p. 145, pi. xi. (animal) (1841) ; Oray, Grey's Austr., 

 A})p. ii. p. 401 (1841) ; Less. N. Tabl. JR. A., Mamm. p, 191 (1842) ; 

 Gray, List Mamm. B. M. p. 100 (1843) ; Wagn. Schr. Sdug. 

 Stipp. iii. p. 33 (1843), v. p. 209 (1856) ; Schinz, 8yn. Mamm. 

 i. p. 613 (1844); Owen, Odontogr. p. 377, .dW. pL xcviii. fig. 4 

 (teeth) (1846) ; Gould, Mamm. Austr. i. pi. iv. (animal) (1846) ; 

 Waterh. N. H. Mamm. i. p. 896, pi. xiv. fig. 1 (animal), and pi. xxi. 

 fig. 1 (skull) (1846) ; Gieh. Odontogr. p. 40, pi. xvii. fig. 2 (teeth) 



