LIFE history OF OATTLE TICK, 31 
Female. Body elliptical, as broad in front ae in back, usually somewhat con- 
Btricted in middle, near 1 \' pair of legs; may attain L3 mm. long, 7.5 mm. broad. Color 
edingly variable; live specimens varj froma tawny yellow (younger forms) to an 
olive green i \ ery old specimens), alcohol specimens from yellow to red or black; the 
excretory system of ten shows through the cuticle as tortuous whitish canals. Dorsal 
shield (scutum) very small, visible as a dark brownish spot in a depression al anterior 
end of median line; usually aboul 1. 1 mm. long by 0.8 to 0.9 m m . broad, decidedly 
emarginate anteriorly to receive capitulum; lateral borders uearly straighl and par- 
allel in anterior portion, from antero-lateral points to eyes, then convergent from 
eyes caudad, forming a more or less bluntly rounded posterior angle in median line; 
cervical grooves divide the anterior half of Bcutum into three more or less equal lon- 
gitudinal fields, and diverge posteriorly; surface of scutum provided with shorl bris- 
tles which arc more numerous near anterior border and uear the eyes than elsewhere. 
Eyes rather small near anterior third of margin of senium. On nearly the ''nine 
length of dorsal surface of body are two antero-posterior grooves, interrupted or uearly 
effaced near plane of IV pair of legs, and ending a short distance from the shield and 
from posterior margins of body; also, an unpaired median groove in posterior half of 
body; all three vary with the muscular contractions and may mere or less com- 
pletely disappear when body is replete. Ventral surface shows four pairs of more 
or less distinct marginal lonstrictions corresponding to the four pairs of legs, the I V 
constriction being mosi marked, antero-median region also depressed at insertion of 
capitulum; vulva small, median, ai plane of coxae 1: sexual grooves corresponding 
to tlie paired dorsal grooves; hut showing some variation in different specimens; 
median groove extending from anus to posterior margin. Anus about on herder of 
second and last thirds of body. Stigmata short oval; stigmal pore slightly crescentic, 
convexity lateral: Btigmal field with numerous larger and smaller wart-like struct ures, 
forming a /.one near the margin. Cuticle of entire body finely wrinkled, hearing short 
hairs. Capitulum very short, about 800// from posterior dorsal margin to anterior 
end of hypostOme; base of capitulum hexagonal, enlarged on its dorsal surface; in- 
serted in emargination of scutum: lateral projections not very prominent. Mandibles 
860// long, digit 120//. Internal apophysis conical (Neumann), bidentate (Fuller), 
with its base near the terminal extremity: external apophysis with three successive 
teeth, one terminal, sub ventral, small; the second stronger; third large. Hypostome 
rather spatulate, broad, a little longer than the palpi, provided on each half with 
four rows of nine to ten nearly regular denticles, which do not extend to the base. 
Palpi very shorl (310//), subcorneal, articles at least as broad as long; first article par- 
tially hidden under the aritero-dorsal border of the base of the capitulum: second 
article pedunculate, dilated in a salient crest in its middle portion, thus forming a 
prominence inward (toward median linn and outward, and provided with strong 
hairs, especially on the inner prominence; third article smaller, subtriangular on its 
■dorsal surface, whore it forms a projection in and out: fourth article -mall, cylindrico- 
conical, infero-terminal. Legs rat her thin, short (pair 1, 2 mm.; pair II, 2.5 mm), yel- 
lowish brown, firsl articles darker than the others. <'ox;e: pair I subtriangular, pos- 
terior border bidentate or biundulate, the division in many cases indistinct. Tarsi 
1 unicalcarate, II to [V bicalcarate. Pulvillum about half_as long a- claws. Stiff 
bristle-like hairs on all art icles. 
EFFECT OF CONTINUOUS COLD AND HEAT ON ENGORGED 
FEMALES. 
Twenty-five ticks were used in the experiments with cold, which 
wore conducted during the month of August, 11)06. A mean tem- 
perature of about 48° F. was maintained, with extremes ranging 
