OF THE MESOZOIC MAMMALIA. 
263 
all the Jurassic genera, but gradually closes into a long, narrowing groove, which sud- 
denly terminates in the middle of the ramus in a foramen beneath the last premolari- 
form tooth. It appears as if the inferior dental artery may have lodged in this groove 
and entered the jaw at this anterior point. From these data, I see no reason for alter- 
ing Professor Owen’s designation of this as the “mylohyoid groove,” but strong rea- 
sons for not attaching great taxonomic value to its presence or absence. 
2. Synonymy. 
For Diplocynodon read Dicrocynodm,. Professor Marsh in a letter to myself, 
dated April, 1888, has substituted the latter name, Mr. Lydekker having called 
attention to the fact that the former is preoccupied by Pomel. Bui. Soc. Geol., 
1846, t. Ill, p. 372. 
For Athrodon read Kurtodon ; see page 208 footnote. 
For Stylodon read Stylacodon ; see page 236 footnote. It is possible that a new 
generic name may be required for the English type of Stylodon, if the American 
types prove distinct from it. 
For TriglypTius read Tritylodon. Mr. Lydekker (op. cit., p. 201) notes that the 
former name is preoccupied for a genus of Diptera. The supposed premolar, described 
upon page 221, probably belongs to the species T. fraasii, Lydekker. 
Errata. 
For Dromatheriu7n read Droinotheriujii throughout. 
Page 191, 18th line, read “ Amphitherium." 
Page 194, 3rd line, for “ genera ” read “ genus.” 
Page 213, 10th line, for “ lower Triassic,” read “lower Jurassic.” 
Page 214, 1st line and footnote, for “ Plagiaulacidcep Marsh,” read '■'•Plagianlacidm, 'Gill.’' 
“’Smithson. Misc. Coll., 1874, p. 27.” 
Page 219, 13th line, 6th word, for “premolars ” read “molars.” 
Page 220, 10th line, for “ median ” read “ intermediate.” 
