OF DENISON UNIVERSITY. 
45 
The eyes are double or single and are sometimes supplied with a 
lense ; they are always furnished with a dark red pigment and, very 
generally, rest directly upon the ganglion. There are occelli at vari- 
ous points in the trochal disc of some species. The sense of touch 
is delicate, and there is often a special tactile tentacle, or palpus with 
minute tactile rods. This may be reduced to a slight papilla or a pit, 
with sensory hairs. No other sensory organs have been discovered, al- 
though Huxley fancies that to be an octocyst, which the Germans call the 
Kalk-beutel,” i. e. the lime-sac. This is a spheroidal sac, contain- 
ing irregular grains of lime. The function is unknown, but it may 
be simply a reserve supply to be used in preserving the rigidity of the 
indurated parts of the body. 
The mouth is more or less ventral, while the anus is dorsal. The 
mouth leads by the pharynx into a roomy and expansible crop or 
directly into the maxtax or masticatory organ, and this is armed with 
chitinous appendages of the most various form, but referable to a sim- 
ple type. Here there is a central anvil-like part called the incus and 
two lateral mallei which consist of a handle (or manubriimi) and a 
head {uncus) which beats upon the incus and reduces the hard parts 
of the food. The maxtax opens into a narrow ciliated oesophagus 
which, in turn, leads to the stomach proper. 
The stomach is sometimes quite distinct from the succeeding parts 
of the ^system, but sometimes can only be distinguished by the large 
size and absorbtive character of its cells. Into the stomach is poured 
the secretion of a pair of glands which may be compared to the so- 
called salivary glands of insects or the liver and salivary glands of ver- 
tebrates. The size of the glands is dependent on the diet of the ani- 
mal. In carnivorous species the glands are small, while in others 
they become quite conspicuous. The intestine is clothed with long 
cilia and opens into the cloaca or common receptacle of the reproduc- 
tive, water vascular, and alimentary systems. In some species, how- 
ever, the stomach is a coecum and has no anus. Males uniformly 
lack the alimentary system and are short-lived creatures of love. In 
some cases evident messentaries support the digestive tract. 
The excretory system consists of a pulsating bladder, opening into 
the cloaca, and two lateral vessels of various form, upon which are 
flagellate chambers which contribute to keep up a circulation between 
the cavity of the body and this vascular system. 
Respiratory and circulatory organs, in the received sense, are absent, 
