516 W. H. Coe — JVeio Palceonemerteans. 



The epithelium of the integument (Plate xv, fig. 5, e) is composed 

 of columnar, ciliated cells and unicellular glands.* The former are 

 the more superficial and form an almost complete layer ; the flask- 

 shaped gland-cells lie among the bases of the ciliated cells and are 

 mostly filled with a secretion which stains deeply. A delicate base- 

 ment membrane lies beneath the epithelium. No cutis is present ; 

 the basement membrane of the integument resting directly upon the 

 body-muscles. 



There are three layers of body-muscles : a thin, outer circular 

 layer (cm'), a strong longitudinal layer (Im), and an inner circular 

 layer (cm). 



The proboscis-sheath is but slightly developed and reaches but a 

 little way back into the intestinal region. Its wall is made up of an 

 outer layer of circular muscles directly continuous with the internal 

 circular layer of the body-wall, and an inner layer of longitudinal 

 muscles made up of a single layer of fibres. The endothelium rests 

 upon a well-developed basement membrane. 



The proboscis is attached to the tissues of the head just in front 

 of the ventral commissure of the brain-lobes. The rhynchodseum 

 bends downward and opens on the ventral side near the tip of the 

 head. The layers of the wall of the proboscis repeat, as in Cere- 

 hratulus, the layers of the body- wall, consisting of a thin external 

 circular, a longitudinal, and an internal circular muscular layer. 

 There is a delicate, outer endothelium bathed in the rhynchocoelomic 

 fluid, and a layer of columnar epithelium lining the proboscis-cavity. 

 Between this epithelium and the internal circular muscular layer lies 

 a pair of nerves in a position similar to that of the lateral cords in 

 the body-wall. The proboscis terminates posteriorly not far back in 

 the intestinal region. The epithelium gradually disappears and then 

 the circular muscular fibres, leaving only the longitudinal fibres 

 which form a slender retractor muscle. This muscle is attached to 

 the dorsal wall of the proboscis-sheath. At the point of attachment, 

 the wall of the proboscis-sheath thickens up and the muscular fibres 

 of the retractor become interlaced with those of the circular layer 

 of the sheath. 



The epithelium of the oesophagus (Plate xiii, fig. 4) consists of 

 ciliated and glandular cells, many of the latter being filled with a 

 clear, mucus-like secretion. These cells are columnar and are 



* In this genus, owing both to the larger size of the cells and to their more simple 

 arrangement, the cell-structure of the various tissues is much more readily made out 

 than in other genera of Nemerteans which I have examined. 



