ZOOLOGY. 



383 



six geuera, liave beeu discovered. These liave beeu named and mdi. 

 cated in the American Journal of Science, as follows: 

 XV. 1878, June (459). Dryolestes priscus. 



xviii. 1879, July (Gl). Stylacodou gracilis. (Stylodontidaj named.) 

 xviii. 1879, Sept. (215). Dryolestes vorax. 



(210). Tinodon bellus) (Tinodontidte named.) 

 xviii. 1879, :N'ov. (390). Ctenacodon serratus. (Plagiaulacidie ^GiU 



1871) renamed.) 

 (397). Dryolestes arcuatus. (Dryolestida? named.) 

 (397). Tinodon robustus. 

 (398). Tinodon lepidus. 

 XX. 1880, Sept. (235). Diplocynodon victor. 

 (230). Stylacodon validus. 

 (230). Tinodon ferox. 

 (237). Triconodon bisulcus. 

 (237). Dryolestes obtusus. 

 In a very recent contribution to the knowledge of tliese types. Pro- 

 fessor Marsh has proposed to difierentiate certain of these forms into 

 two orders, one of which he nas named Fantotheria and the other AUo- 



tlieria* . 



The Fantotheria are distinguished by "(1) cerebral hemispheres 

 smooth ; (2) teeth exceeding or equaling the normal number, 41 ; (3) 

 premolars and molars imperfectly differentiated ; (4) canine teeth with 

 bifid or grooved fangs; (5) rami of lower Jaw unanchylosed at symphysis; 

 -(0) mylohyoid groove distinct on inside of lower jaws ; (7) angle of lower 

 jaw without distiuct inflection ; (8) condyle of lower jaw near or below 

 horizon of teeth ; and (9) condyle vertical or round-not transverse." 

 To the group thus defined Professor Marsh thinks that, with tlie ex- 

 ception of a very few aberrant forms, the known Mesozoic mammals 

 may be mostly referred. 



The Allotheria are distinguished by having " (1) teeth much below the 

 normal number; (2) canine teeth wanting; (3) premolar and molar 

 teeth specialized; (4) angle of lower jaw distinctly inflected; (o) 

 mylohyoid groove wanting." The group so distinguished is proposed tor 

 the genus Flagiaulax, represented by a species originally described 

 by Owen, and of which representatives have been likewise found m 

 America, 'and to it are referred the new genus Ctenacodon of Marsh, 

 " and possibly one or two other genera." 



It will be out of place to traverse the conclusions of Professor Marsh, 

 but those best acquainted with the mammals will agree that whatever 

 may be the relations of the forms above differentiated, it still remains 

 to be proved that they are entitled to ordinal distinction, for certainly 

 the characters adduced are not generally considered to be entitled to 

 such value by the majority of modern therologists. 



'Marsh (O C). Notice of Jurassic Mammals representing two new Orders. Am. 

 Journ. Science, (3,) vol. xx, pp. '235-239, Sept. 1880. (See, also, vol. xv, p. 459; vol. 

 xviii, pp, 60, 215, 396, 1879.) 



