542 H. LYSTER Jameson, 



sensory cells, which are strikingly diö'erentiated from the surrounding 

 epidermis when stained by Heidenhain's iron-haematoxyliu method 

 (Fig. 6). 



Each cell consists of a spindle-shaped body containing a large 

 ovate nucleus, the structure of which is remarkably granular, and a 

 process extending outwards and piercing the cuticle as a short stout 

 hair which projects but a short way above its surface. To these 

 sense organs nerves are given off from the lateral trunks of the 

 proboscis, and occasionally fibres (Fig. 6 gang.c) can be seen dis- 

 appearing among the inner swollen ends of the cells. One or more 

 of the gland cells frequently lies in the neighbourhood of the sense 

 organs, but these glands have no essential connexion with them. These 

 sense organs resemble those of Thalassema diaphanes Sluiter (15, 

 p. 245 — 246, tab. 3, fig. 4 b) in the absence of associated glands, 

 rather than the "becherförmige Sinnesorgane" of Echiurus described 

 by Spengel (17). 



The cutis (Fig. 1 and 2 cu). I have little to add to the observ- 

 ations of previous writers on this tissue. It is a hyaline faintly 

 staining layer which lies under the epidermis and develops to consider- 

 able dimensions in the body wall. Its fine structure is fibrillar and it 

 seems to be composed of stellate connective tissue cells with thread- 

 like processes. In the interspaces between the papillae, where it is 

 thinner than elsewhere, the fibrillae tend to adopt a parallel course, 

 which may readily be mistaken on superficial observation for a nervous 

 tissue. Genuine nerves however occur also imbedded in the cutis. 

 The nuclei are mostly elongated in form, and do not stain very deeply 

 in comparison to those of the epidermis. Internally the cutis goes 

 over into the connective tissue matrix in which the muscles lie em- 

 bedded. This can be much more plainly seen in the proboscis, where 

 the muscles extend up between the root-like processes of the "Faden- 

 zellen", and where the cutis as such has no real existence. 



II. The Musculature of the Body Wall. 



The musculature of the body wall consists of an outer layer of 

 circular muscles, a layer of longitudinal muscles, and an inner layer 

 of oblique muscles. The last are only slightly oblique, so that on 

 superficial observation they might be easily interpreted as circular. 

 Nevertheless they do not quite coincide in their direction with the 

 outer circular fibres, but are inclined outwards and slightly backwards 

 from the median ventral line, crossing in a confused manner in the 



