W. B. Coe — Anatomy of Cerehratuhis lacteus. 481 



The Integument. 



The integument consists of an outer ciliated and glandular epithe- 

 lium, with its underlying basement membrane and double set of 

 muscles, and an inner cutis ; the latter possessing a deep layer of 

 glands and a thick network of fibres. 



The epithelium (Plate XI, fig. 1 ; Plate XV, fig. 1, e) is made up 

 of long ciliated cells and of two kinds of gland-cells, together with 

 delicate supporting fibres from the basement layer beneath. Each 

 ciliated cell (Plate XY, fig. 2, ce) is long and slender except near its 

 free surface, where it is broad and thick. The free surface is cov- 

 ered with cilia, each cilium being attached to the cell by a slender, 

 rod-like process with a knob at the end on which the cilium rests. 

 A row of such knobs is readily mistaken for a section of a thin 

 membrane and has been repeatedly described as a cuticle. The cell 

 is contracted below to a slender fibre, often branched near its end, 

 where it is attached to the basement membrane beneath. An oval 

 nucleus lies in the lower part of the body of the cell. 



The unicellular glands, " goblet-cells " (Plate XV, fig. 2, g,g'), are 

 mostly covered above by the overhanging ciliated cells, and are of 

 two varieties which are readily distinguished by the staining prop- 

 erties of their contents. One variety [g) is characterized by its 

 coarse granular secretion which stains deeply with hsematoxylin, 

 while the other ((/') possesses a homogeneous, non-staining secretion in 

 a fairly regular, oval or elongated, solid mass which shows a striking 

 resemblance to the rhabdites of the Rhabdocoela.* Both varieties 

 of gland-cells are elongated and broadened below, with their oval 

 nuclei pushed well down toward the bottoms of the cells, which are 

 often continued, as are the ciliated cells, into slender, fibre-like pro- 

 cesses. The secretion, especially of the latter variety of glands, is 

 often pressed partl37^ out of the cell and projects on the surface 

 among the cilia. Slender masses of deeply stained secretion from 

 the cuticular glands are often met with among the epithelial cells. 



Amongst the bases of the epithelial cells we find numerous nuclei 

 different both from those of connective tissue and from those of 

 the epithelial cells. These nuclei belong, in part, to interstitial sup- 

 porting cells (Plate XV, fig. 1, ^), and, when we consider the number 

 of nerve fibres with which the epithelium is provided, it seems quite 

 probable that some of them belong to cells connected with the nerv- 

 ous system, either to the sensory cells themselves or to some other 



* Cf. Lang (14). 



