OP ARTS AND SCIENCES. 93 



a tubular neck is seen leading to the surAice, and a minute opening is 

 sometimes visible. In sections the glands are seen to contain pale 

 nuclei, usually near tbe bottom or on one side, and their contents ap- 

 pear granular and not stainable. They are very conspicuous on the 

 frontal lobe in the living animal, and appear as sacs, sometimes slightly 

 lobed, and always filled with rounded granules. When the animal is 

 strongly compressed under a cover-glass, the contents of these glands 

 are occasionally forced out through the neck. The nuclei have not 

 been seen in the glands in the living animal. 



The appendages of the dermis are the podal stylets, bristles, hairs, 

 and cilia. The hairs are found over the whole body, but they are 

 more numerous on the frontal lobe and on the digitiform appendages 

 of the pavilion than elsewhere. They may possibly serve as sense 

 organs. Cilia are found over the whole border and interior surface of 

 the pavilion, and on the extreme front end of the pre-oral lobe. 



The muscular system consists of a layer of annular fibres immedi- 

 atel}' beneath the dermis, and, still deeper, a layer of longitudinal 

 fibres. There are also special muscles for moving the bristles, the 

 pharynx, and the supra-cesophageal ganglion. Muscular fibres also 

 help to form the partial partitions between the segments, and in the 

 interseptal regions run from the body wall to the alimentary canal, sus- 

 pending the latter. The fibres in the annular layer (PI. II. figs. 11, 

 16, 17) are not so large as those in the longitudinal layer, and are 

 seen with difficulty, but they show plainlj^ in specimens that have been 

 mounted for some time in balsam. The layer of longitudinal fibres is 

 divided by the four rows of bristle sacs into four longitudinal bands, a 

 dorsal, a ventral, and two lateral. These bands, as is easily seen in 

 specimens mounted entire in balsam, are sharply marked off from one 

 another by spaces that contain no longitudinal muscular fibres. Each 

 band is divided into two secondary bands by spaces that contain no 

 muscular fibres, or much fewer and narrower ones than are found 

 elsewhere. This division into secondary bands is not always visible in 

 specimens mounted entire, but is usually evident in such specimens 

 near the posterior end of the body. In cross sections, however, this 

 division becomes plain. The spaces between the halves of the lateral 

 bands are occupied by the nervous lateral lines (PI. II. fig. 17, l. In.). 

 The space dividing the ventral band lies immediately beneath the ven- 

 tral nervous cord, and is the plainest of the four. This arrangement 

 of longitudinal muscular bands agrees with that found by Perrier 

 ('72, p. 72) in Dero obtusa. 



The special muscular fibres for moving the pharynx and brain are 



