oxox LIFE HISTORY OF CATTLE TICK. 31 
Female.—Body elliptical, as broad in front as in back, usually somewhat con- 
stricted in middle, near IV pair of legs; may attain 13 mm. long, 7.5mm. broad. Color 
exceedingly variable; live specimens vary from a tawny yellow (younger forms) to an 
olive green (very old specimens), alcohol specimens from yellow to red or black; the 
excretory system often shows through the cuticle as tortuous whitish canals. Dorsal 
shield (scutum) very small, visible as a dark brownish spot in a depression at anterior 
end of median line; usually about 1.1 mm. long by 0.8 to 0.9 mm. broad, decidedly 
emarginate anteriorly to receive capitulum; lateral borders nearly straight 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 scutum into three more or less equal lon- 
gitudinal fields, and diverge posteriorly; surface of scutum provided with short bris- 
tles which are more numerous near anterior border and near the eyes than elsewhere. 
Eyes rather small near anterior third of margin of scutum. On nearly the entire 
length of dorsal surface of body are two antero-posterior grooves, interrupted or nearly 
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 more or less com- 
pletely disappear when body is replete. Ventral surface shows four pairs of more 
or less distinct marginal constrictions corresponding to the four pairs of legs, the IV 
constriction being most marked, antero-median region also depressed at insertion of 
capitulum; vulva small, median, at plane of cox I; sexual grooves corresponding 
to the paired dorsal grooves; but showing some variation in different specimens; 
median groove extending from anus to posterior margin. Anus about on border of 
second and last thirds of body. Stigmata short oval; stigmal pore slightly crescentic, 
convexity lateral;, stigmal field with numerous larger and smaller wart-like strictures, 
forming a zone near the margin. Cuticle of entire body finely wrinkled, bearing short 
hairs. Capitulum very short, about 800s from posterior dorsal margin to anterior 
end of hypostome; base of capituluni 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, subventral, 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 short (3102), subconical, articles at least as broad as long; first article par- 
tially hidden under the antero-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 line) and outward, and provided with strong 
hairs, especially on the inner prominence; third article smaller, subtriangular on its 
dorsal surface, where it forms a projection in and out; fourth article small, cylindrico- 
_ conical, infero-terminal. Legsrather thin, short (pair I, 2 mm.; pair II, 2.6 mm), yel- 
lowish brown, first articles darker than the others. Coxee: pair I subtriangular, pos- 
terior border bidentate or biundulate, the division in many cases indistinct. Tarsi 
I unicalearate, 11 to IV bicalearate. Pulvillum about half as long as claws. Stiff 
bristle-like hairs on all articles. 
EFFECT OF CONTINUOUS COLD AND HEAT ON ENGORGED 
FEMALES. 
Twenty-five ticks were used in the experiments with cold, which 
were conducted during the month of August, 1906. A mean tem- 
perature of about 48° F. was maintained, with extremes ranging 
