EARLY RECORDS 7 



even from the standpoint of color, since in subsequent crosses 

 with pigmented forms they give offspring with different color 

 markings according to their several latent characters. 



On the other hand it may be fairly said that as yet we have 

 no evidence for any correlation of the somatic characters so far 

 studied, with those slight differences hi gametic composition of 

 the common albino strain which we can recognize. It is to be 

 noted moreover that the difficulty which thus appears in the 

 case of the albino rat repeats itself for other mammals also, and 

 therefore it does not constitute a peculiarity of this animal. 







CLASSIFICATION ! REFERENCES 



Alston, 1879-1882. Blasius, 1857. Doncaster, '06. Erxleben, 1777. Fischer, 

 1803. Geoffrey, 1812. Gesner, 1551. Hatai, '07. Hollister, '16, '16 a. 1'Isle, 

 1865. Linnaeus, 1758, 1766. Lloyd, '12. Longman, '16. Millais, '05. Miller, 

 '10. Mudge, '10. Pallas, 1778. Rehn, 1900. Topsell, 1658. Trouessart, 1881, 

 1897, '10. Tullberg, 1900. 



EARLY RECORDS AND MIGRATIONS OF THE COMMON RATS 



The common wild rats in the United States usually live in 

 close association with man. There are two species of these, 

 both of which have been introduced from Europe. These are 

 Mus rattus (Linnaeus, 1758; 1766 = Mus rattus rattus, Millais, 

 '05) together with its gray form, Mus alexandrinus (Geoffrey, 

 1812; = Mus rattus alexandrinus, Millais, '05) and Mus nor- 

 vegicus (Erxleben, 1777 = Mus decumanus, Pallas, 1778). 

 This last species is our common gray, brown or Norway rat. 

 In addition to these, all of which are wild, there is a fourth 

 form the albino rat (Mus norvegicus albinus) a variety of 

 Mus norvegicus (Hatai, '07) which is known at present only 

 as a domesticated strain (Donaldson, '12 b). 



Mus rattus the house rat the first species described hi 

 western Europe, is probably indigenous to India. 1 As now 



1 Fossil remains of the rat (Mus rattus) are reported in the pliocene in Lom- 

 bardy (Cornalia, 1858) and in the quaternary at Molina di Anosa near Pisa (For- 

 syth Major) and again from the pleistocene cave deposits of the island of Crete 

 (Bate, '12). This species appears in glacial times (Diluvialzeit) and in associa- 

 tion with man in the remains of the Lake dwellers in western Germany and in 

 Mecklenburg (Blasius, 1857). It is reported also from the diluvial deposits in 

 Bohemia (Woldfich, 1880). 



