1 
2S 
jointed and provided vith muscles, terminate in pinchers vdth ser- 
rated jaws in the female. In the capitelhun they lie in chitinous 
sheaths and are prolonged posteriorly, to he attached by tendinous 
expansions to the tmder sinface of the scuttun. Muscles attached 
to the same point serve to retract or protrude the mandibles. 
The ventral aspect of the capitelhun terminates in a bifid Tiypo- 
stome or maxifiie (pi. vi). The maxillcn are situated, one on either 
side of the mouth opening and form part of its lateral boimdarv. 
They are acutely pointed and serve as piercing organs. Between and 
dorsad of the maxilla? is a single elongated organ, the lingula or 
tongue (pi. VI , which presents a median groove. Its surface is 
covered with minute papilla?. The outline of the mouth opening 
is somewhat triangular, the borders being formed by fringed mem- 
branous folds. 
The phaetxx. — The pharynx is situated just posterior to the mouth, 
in which it terminates. It lies alniost entirely in the capiteUum. 
forming a canal In the lower portion. It is T shaped (pi. vii^ fig. 2) on 
cross section and its walls are connected by a series of transverse mus- 
cular bands with the chitinous covering of the capitellum. These 
muscles serve to pull apart the walls of the pharynx and produce 
suction. Interspersed with the transverse muscles are a series of 
circular muscular btmdles (pi. vii. fig. 1) capable of constrictmg the 
pharynx. 
The esophagus. — Posteriorly the pharynx terminates in a slender 
tube, the esophagus «pl. vii, fig. 1;. This m ttun communicates with 
the ventnculus or stomach. Surrotmding the esophagus is a large 
ganglion or hr am. 
The ventriculus is a thm-walled sac consisting of a central and two 
lateral portions (pi. vni. ng. 2 ■. The former conmiunicates anteriorly 
and inferiorly with the esophagus. The diverticula are prolonged 
anteriorly and posteriorly and commimicate with the lateral aspect of 
the ventriculus. The wide central portion (pi, vii. fig. 1) extends 
from the brain to the middle third of the thorax, resting upon the 
inner skeletal plate. Regarding each lateral cfivertictdmn as two 
projections (anterior and posterior • from the ventriculus, there are in 
addition two others, viz. the mechan anterior projection to join the 
esophagus and a posterior projection terminating m the colon, which, 
in ttun. empties into the excretory Madder. TVhen the uterus con- 
tains a large embryo the ventriculus is somewhat distorted and 
displaced. 
The ventriculus and its lateral prolongations are fined with a single 
irregular layer of large epithelial cells with faintly staining retictdar 
and vacuolated protoplasm and inconspicuous nuclei. The cells rest 
upon a delicate basement membrane. Encircfing the digestive tract 
are a series of minute parallel muscular fibers, each one isolated and 
