The annals and magazine of natural history : zoology, botany, and geology . haracteristicof I he larger species. Measurements.—Hind foot measured on the skin about 00 mm. Measurements of skull (with corresponding dimensions of a skull ofansorgei in parentheses).—Condylo-basal length 687 (77) mm.: zygomaticbreadth 33 ca. (38) ; interorbital constriction 102 (114) ; mastoid breadth242 (27-1) ; nasal 28x 10-1 (33X 10-5); incisor to 388 (42*3) ; dia-stema 22 (239); length of anterior palatal foramina 88 (82) ; length ofpreorbital fossa for masSeter medialis 14 (14) ; least diameter of zygo-mat
The annals and magazine of natural history : zoology, botany, and geology . haracteristicof I he larger species. Measurements.—Hind foot measured on the skin about 00 mm. Measurements of skull (with corresponding dimensions of a skull ofansorgei in parentheses).—Condylo-basal length 687 (77) mm.: zygomaticbreadth 33 ca. (38) ; interorbital constriction 102 (114) ; mastoid breadth242 (27-1) ; nasal 28x 10-1 (33X 10-5); incisor to 388 (42*3) ; dia-stema 22 (239); length of anterior palatal foramina 88 (82) ; length ofpreorbital fossa for masSeter medialis 14 (14) ; least diameter of zygo-matic plate 6-2 (81) ; molar crowns 105 (128). XXVIII.— The Method of taking the Incisive Index inRodents. By Oldfield Thomas. (Published by permission of the Trustees of the British Museum.) The angle at which rodent incisors protrude from the jawhas long been recognized as an important character of diffe-rent groups, but it is only recently that an attempt has beenmade to define that angle more exactly, instead of merelyspeaking of incisors thrown forward and so Diagram showing method of taking incisive index in rodents, This angle, when exactly measured and defined, provesto be exceedingly useful as a systematic character, but it isessential that the way it is taken should be clearly understood, 200 Mr. II. E. Andievves on Oriental Caiabidae. Tlie line of the grinding-edge of tlie cheek-teeth being takenas a basis, the angle was in the first paper * deduced fromtliat formed by the terminal partof the incisor ; but later on fI have found it better to use the whole extruded part of thelatter tooth. But since the description of the taking of theangle might be easily misinterpreted, I have now had pre-pared the accompanying diagram showing the way the processis carried out and the angle read off. This will, I hope,facilitate the work of other observers. Incisors thrown forward are those with a high resultantangle, and might be called, as suggested in 1918 J, pro-odont, u
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