148 JOURNAL OF THE WASHINGTON ACADEMY OF SCIENCES VOL. 13, No. 8 
This genus is established for the reception of the peculiar Octodont in- 
festing species, Hoplopleura alata Ferris and H. audax Ferris. The great 
modification of the second pair of pleural plates, not so much in size but in 
type, is the outstanding feature in this genus. This modification has resulted 
in the peculiar shifting of the position of the pleural setae so that they have 
become dorso-marginal. 
Eulinognathus americanus, sp. nov. 
Forehead very short and cone-shaped; postantennal region of head as 
broad as long. Antennae equal to the head in length; first segment broader 
than long, second segment of about equal breadth and length. Thorax 
about as broad as long; sternum without anterior process between first coxae 
but with a posterior process which extends between the third coxae for a 
part of its length. Abdomen much longer than broad. Typical pleural 
plates with spiracular opening slightly in front of the middle, with two cusp- 
like posterior lobes and short, stumpy, truncate pleural setae, scarcely half as 
long as the pleural plates themselves. Abdominal setae curved near their 
bases, flattened and parallel-sided beyond and truncate distally, each being 
about as long as the abdominal segment on which it is situated. Gonopods 
of female short and stumpy and with a few spinous setae. Second legs 
intermediate between first and third. Claw of third leg neither toothed or 
appendiculate. Length of female 0.95 mm.; width of female 0.39 mm. 
Type host and type locality: From Ctenomys brasiliensis (Cat. No. 3252, 
1939 U.S.N.M.) taken at Salade River, Paraguay. 
Type.—Cat. No. 23761, U.S.N.M. 
The genus to which this species belongs has been represented in the past 
by only two species, one of which came from a host of the rodent family 
Pedetidae and the other from the rodent family Dipodidae. The host of the 
new species here described belongs to the rodent family Octodontidae. Only 
a single female specimen taken. 
Phthirpediculus, gen. nov. 
Antennae long and distinctly five-segmented. Thorax and abdomen dis- 
tinctly separated; segments two, three and four of abdomen distinct and 
bearing its pair of spiracles in the normal lateral position; abdomen with 
well developed pleural plates on segments three to eight and without lateral 
lobes. Typical abdominal segments provided with a single transverse row 
of setae both above and below. Genital armature of male with a basal 
plate composed of two distally united, parallel rods; with large, more or less 
blade-like parameres; and with conspicuous, heavily chitinized pseudopenis. 
First pair of legs very small, the other two pairs much enlarged; all legs 
attached to thorax in a ventro-lateral position. 
Type of genus: Phthirpediculus propithect, new species. 
This genus, represented only by the new species here described, is inter- 
mediate between Pediculus Linnaeus and Phthirus Leach, having the long 
abdomen with pleural plates as in Pediculus, but the small anterior legs of 
Phthirus. . 
