578 MURID^— EPIMYS 



effective copulation {i.e. with the production of a vaginal 

 bouchon), but the unions were infertile ; his friend C. Mailles 

 was also unsuccessful. Iwanoff {Arch, des Set. Biol., xii., 1907, 

 376 ; Marshall, 609) artificially inseminated a white mouse 

 with spermatozoa of a white rat ; two hybrid young, inter- 

 mediate in size between mice and rats, were produced after a 

 pregnancy of twenty-seven days. 



Exceptional variation :— Specimens of rats and mice with 

 the skin corrugated and devoid of hair have been occasionally 

 reported ; for instances and references, see Proc. Zool. Soc, 

 London, 1856, 38, and 1903, 336. Albinic or melanistic indi- 

 viduals are not uncommon. Tailless and other physically 

 deformed rats are known, but such deformities appear usually 

 to be the results of injuries. 



Two species have to be described as British, viz., the Black 

 or Ship Rat (E. rattus), and the Brown or Common Rat 

 {E. norvegicus). 



I. THE BLACK OR SHIP RAT 



EPIMYS RA TTUS, Linnasus. 



For synonymy, see below under sub-species. 



Le Rat Noir of the French : die Hausratte of the Germans. 



Terminology: — Rats (late Latin ratus and rattus, of uncertain 

 origin (A^. E. Diet.), but possibly derived from rapere (de I'lsle), radere 

 (Skeat), or rodere {Cent. Diet.) ) are not mentioned in the Epinal Glossary 

 (about 700 A.D.), where the word mus is applied to shrews. They 

 appear first about 1000 a.d., in Archbishop ^Ifric's Voeabulary (ed. 

 Wright- Wiilcker, 1884), where raturus = " rst." According to the 

 New English Dictionary the word appears to have been adopted from 

 the Latin first by the Teutonic languages in the form ratton, and later 

 by the Rohiance tongues ; the converse view, however, has been 

 advanced by de I'lsle (see p. 582), and it seems probable that prior to 

 the Crusades the name was applied to the House Mouse (see p. 579). 

 In the Latin writings of Giraldus Cambrensis (i 147-1223) rats are 

 perhaps first clearly distinguished from mice ; while in the Vision of 

 Piers Plowman (1377), B. Prol., 146 and 200, "a route of ratones. . . . 

 And smale mys with hem " are mentioned. Shakespeare, Tempest, 

 Act i., sc. 2, 147, 1610, has : " Nor tackle, sayle, nor mast ; the very rats 

 instinctively have quit it " ; and also Measure for Measure, Act i., sc. 2 : 

 " Rats that ravin down their proper bane." 



