. A history of British mammals . Edwardes, Ann. Soc. Nat.,1871, XV., art. 7); and Biarritz (aspecimen from this last placeseen by Barrett-Hamilton). There can be little doubtthat it is of frequent occurrence,but is confused with E. rattusor Arvicola amphibius; for in-stance, when observed in theZoological Gardens of Londonit has done duty for E. rattiis(see Millais, ii., 211 ; Pocock, inlit., to Barrett-Hamilton). Itseems to be a western develop-ment of the species, and toafford a close parallel, assuming de Ilsles view to be correct, to therelations subsisting between E. r. rattus and the wil
. A history of British mammals . Edwardes, Ann. Soc. Nat.,1871, XV., art. 7); and Biarritz (aspecimen from this last placeseen by Barrett-Hamilton). There can be little doubtthat it is of frequent occurrence,but is confused with E. rattusor Arvicola amphibius; for in-stance, when observed in theZoological Gardens of Londonit has done duty for E. rattiis(see Millais, ii., 211 ; Pocock, inlit., to Barrett-Hamilton). Itseems to be a western develop-ment of the species, and toafford a close parallel, assuming de Ilsles view to be correct, to therelations subsisting between E. r. rattus and the wild-coloured formsof that species. The skull (Fig. 91) is strongly built and of relatively large size (thecondylo-basal length usually more than 45 mm.). Compared withE. rattus, the brain-case is relatively narrower; the parietal region ismuch less conspicuously vaulted, and the rostrum is larger, especiallydeeper and broader. The dorsal profile is flatter and more nearlyhorizontal throughout. The masseter and temporal muscles are. Fig. 91.—Skull and Mandihle of Epimysnorvegkus (life size). Reproduced fromMillers Catalogue of Mammals of WesternEurope, by the kind permission of theTrustees of the British Museum. THE BROWN OR COMMON RAT 615 relatively larger and more powerful than in rattus. The zygomaticarches are therefore heavier, and the masseteric plate is wider inproportion to its height. The temporal fossse are more extensive,the parietal crests, which continue the supra-orbital ridges backwardsto the hinder edges of the squamosals, running at a higher level(in an old skull of E. r. rattus the greatest distance between these crestsequals 88 per cent, of the cranial width, but in a similar skull ofnorvegicHs it equals 73 per cent, only); the greatest distance betweenthese crests is about equal to the length of a parietal measured alonga crest. The posterior border of the interparietal is nearly straightinstead of boldly convex, and the backward deflection of the centralpart
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Keywords: ., bookcentury1900, bookdecade1910, booksubjectmammals, bookyear1910
