58 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I23 



Records of Specimens Examined 



One male from Eliomys quercinus, Upper Bavaria, Waldmiichen, Germany, 

 Aug. 25, 1948, Gerd Heinrich. One female from Clethrionomys (= Evotomys) 

 glareolus hclvcticus Zermatt, Switzerland, Sept. 18, 1917, K. Jordan and N. C. 

 Rothschild. 



Discussion of the hamijer group 



The hamijer group of Peromyscopsylla is here defined as that group 

 of Peromyscopsylla in which the genal process is concealed by the 

 upper genal spine, the upper genal spine is the longer, there are nor- 

 mally three subdorsal bristles between the spiniform bristles and an- 

 tennal margin on the dorsal margin of the head and four regular rows 

 of bristles on the postantennal area of the head. Aedeagal similarities 

 are discussed in the section below. Included in this group are P. 

 hamijer ssp. (from eastern and western United States, Canada, and 

 Korea), ostsibirica ssp. (from Alaska and Siberia), and bidentata 

 (from Europe). P. hamijer has been arbitrarily selected as "parent 

 species" of this group purely for the sake of convenience and not with 

 the belief that it is necessarily such in the evolution of the group. 



P. bidentata, the only described European form belonging to this 

 group, is quite distinct from hamijer in both male and female. In the 

 female the differences may seem of rather unimportant proportions, 

 i.e., merely differences based upon the shape of the seventh sternum, 

 but it should be remembered that hamijer hamijer and hamijer vigens 

 females are morphologically indistinguishable, although the males of 

 these two subspecies may be determined readily (see descriptions and 

 figures of h. hamijer and h. vigens). P. ostsibirica ssp. from Alaska 

 and Siberia differs from both hamijer ssp. and bidentata but is un- 

 doubtedly more closely related morphologically to hamijer than to 

 bidentata. Again, the females of o. longiloba differ from hamijer ssp. 

 in like degree as hamijer differs from bidentata, but also differ from 

 bidentata in that the apical bristles on the second antennal segment 

 are three-fourths the length of the club in the female, not reaching the 

 apex of the club ; and one-half length of club, not three-fourths length, 

 in male. This nonsexual character in this case, considered with other 

 characters, is believed to be of higher than subspecific level. It is ex- 

 pected that 0. ostsibirica from Siberia will show the same variation. 



Owing to its probably longer isolation, P. bidentata is regarded at 

 present as being most distinct from the "parent species," hamijer. P. 

 ostsibirica ssp., on the other hand, may not have been separate for so 

 long a time and hence is more similar to hamijer. The subspecies of 

 hamijer itself are probably on the way to forming separate species, but 



