Family Hystrichopsyllidae Tiraboschi 79 



Female. In the single specimen at hand the preantennal 

 region of the head is armed with a distinct row of about seven 

 bristles, below which are two widely separated much stouter 

 ones which may be part of another row. Frons and gena with 

 numerous scattered small setae. Genal ctenidium consisting of 

 five long slender spines. Posterior margin of the antennal 

 groove with a number of small setae. Postantennal region ap- 

 parently armed with two rows of bristles in addition to the mar- 

 ginal row. Genal process prominent and acuminate (Plate 

 XXI, fig. 108) . Pronotum armed with two rows of bristles 

 and ctenidium of about fifteen spines on a side. Meso- and 

 metanotum each armed with four or five rows of bristles. Each 

 abdominal tergite armed with three rows of bristles. Second 

 abdominal tergite with five to seven lateral teeth, third with 

 four, and fourth with one or two on a side. Abdominal sternites 

 armed with numerous bristles. Sternite VII without a deep 

 sinus, the posterior margin uneven in outline. Head of the 

 receptaculum seminis more or less quadrangular, much wider 

 than the tail. For further details concerning the structure of the 

 female genitalia, see Plate XXI, fig. 107. 



The above description and the accompanying illustrations are 

 based on a female taken from "Microtus pennsylvanicus" at 

 Adirondack Lodge, Essex County, New York, loaned through 

 the courtesy of Dr. Karl Jordan. 



Male. In his description of the male of the eastern sub- 

 species, Dr. Jordan (1929) states: "About the middle of clasper 

 and oblique row of three long bristles, in front of them four to 

 six much smaller ones and a few marginal hairs; near and at 

 posterior margin from four to six bristles, of which the two 

 upper ones are moderately large. Ventral arm of IX st. char- 

 acteristic; with four each side and the apex enlarged upwards 

 on (each side) into a compressed cone which leans slightly 

 distad." His illustration is redrawn in Plate XXI, fig. 106. 



Eastern hosts. Short-tailed Shrew ("Blarina brevicauda") , 

 Meadow Mouse ("Microtus pennsylvanicus") , White-footed 

 Mouse (Peromyscus leucopus noveboracensis (Fischer) ) . 



Eastern locality. New York. 



Type material. The eastern subspecies of this species de- 

 scribed by Jordan as H. gigas tahavuana was based upon a 

 male and female from "Blarina brevicauda" and female from 

 "Microtus pennsylvanicus" at New York, which are in the 

 N. C. Rothschild Collection (British Museum) . 



