882 ANATOMY AND DEVELOPMENT 



bodies. The part of each gland which bends inwards must be 

 regarded as the duct. 



The cells lining the ducts are considerably less columnar 

 than those of the gland proper. Their nuclei (fig. 14) are 

 situated at the free extremities instead of at the base of the cells, 

 and they are without secretory globules. The cells lining the 

 ducts of the salivary glands pass, without any sharp line of 

 demarcation, into those of the oral epithelium, which are flatter 

 and have their nuclei placed in the middle. 



The Pharynx. The Pharynx is a highly muscular tube (fig. 

 7) with a triangular lumen (figs. 14, 15), .which extends from 

 the mouth to about half way between the first and second pair 

 of legs. It is lined by a flattish epithelium bounded by a cuticle 

 continuous with that of the mouth. On the dorsal side is a 

 ridge projecting into the lumen of the pharynx. This ridge 

 may be traced forwards (PI. 49, figs. II 14) into the tongue, 

 and the two grooves at the side of this ridge, forming the two 

 upper angles of the triangular lumen, may be followed into those 

 at the sides of the tongue. The muscles of the pharynx are 

 very highly developed, consisting of an intrinsic and an extrinsic 

 set. The former consists, as is best seen in longitudinal sections, 

 of (PI. 51, fig. 23) radial fibres, arranged in somewhat wedge- 

 shaped laminae, between which are rings of circular fibres. The 

 latter are thicker externally than internally, and so also appear 

 wedge-shaped in longitudinal sections. Very characteristic of 

 the pharynx are the two sympathetic nerves placed close to the 

 two dorsal angles of the triangular lumen (fig. 14, sy). 



The pharynx of Peripatus is interesting in that it is unlike, 

 so far as I know, the pharynx of any true Arthropod, in all of 

 which the region corresponding with the pharynx of Peripatus 

 is provided with relatively very thin walls. 



The pharynx of Peripatus has, on the other hand, a very 

 close and obvious resemblance to that of many of the Chaeto- 

 poda, a resemblance which is greatly increased by the character- 

 istic course of the sympathetic nerves. 



The form of the lumen, as already pointed out by Grube, 

 resembles that of the Nematoda. 



Ttte (Esophagus. Behind the pharynx there follows a narrow 

 oesophagus (fig. 7, o e] shewn in section in fig. 16. It has some- 



