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 manubiHuni) 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, 



