250 



Mr. G. A. Bouleiiii'cr on the Races and 



exceptions occasionally occur in the typical form (Poitiers, 

 Bologna) and in the var. ridibunda (Alemtejo, Majorca, 

 Rahamna in Morocco). The outer metatarsals are separated 

 nearly to the base in II. escuhnta, only in their distal half in 

 R. temporaria and R. arvalis, the other European species 

 filling up the gap between the two extremes. 



Integument and Markings. 



The elongate glandules or interrupted longitudinal glan- 

 dular folds on the back*, afford, generally speaking 1 , a good 

 distinctive character for the var. chinensis, but they may be 

 very feebly marked or almost obsolete in some specimens 

 (Kin Kiiiug, Yokohama), and they are occasionally fore- 

 shadowed in the var. ridibunda (Beit Jenn, near Damascus), 

 so that the two forms are completely connected in this respect. 



I may point out another character, hitherto overlo >ked, 

 which affords an absolutely constant distinction between the 

 typical form and the var. chinensis. 



Fiur. 5. 



Posterior extremities of dorso-lateral folds in specimens from Berlin, 

 var. ridibunda (a), Cadillac, var. ridibunda (b), and Vienna, 

 f. li/pica (c). 



In the former, and also in the var. lessonce, the glandular 

 dorso-lateral fold ends abruptly at some distance in front of 

 the thigh, and it is often followed by a detached portion 

 parallel with it but nearer to the mid-dorsal line and extend- 

 ing on the base of the thigh. In the var. chinensis the fold 

 extends uninterrupted to the hip, or, if broken up posteriorly, 

 without any deviation from the straight line. Now, this 

 striking difference is completely bridged over when we take 

 the var. ridibunda, as well as the var. saharica, into con- 

 sideration. Some specimens have the fold continuous and 



* A very variable feature in the American representative of H. escu- 

 lenta, It. hahcina, L. 



