NOTE ON A NEW BRITISH BCHIUROID GEPHYREAN. 371 



coloured, and the colouring is not so uniform, but is rather 

 streaky. It is greener along the edges and paler (pale greyish 

 green, becoming in places almost a dirty white) along the centre. 



Size. — The length of the body when complete was probably 

 about 12 cm. ; the thickness varies from 5 to 15 mm. The 

 length of the proboscis is fully 9 cm., and its breadth in the 

 flattened part varies from 15 to fully 20 mm. The narrow 

 basal part is about 5 mm. in diameter. 



Apertures. — The mouth is placed at the anterior end of 

 the body, in the median ventral line, beneath the base of the 

 proboscis (which is a pre-oral lobe). The cloacal opening is 

 median and posterior (PI. 27, fig. 6). 



The two genital apertures are placed ventraliy, one at each 

 side of the middle line, and a little behind the mouth. Each 

 genital aperture has, projecting from the integument beside it, 

 a large curved seta, or genital bristle, of a golden colour 

 (figs. 5 and 13). 



Integument and Muscles. — The body-wall is thick, 

 especially at the posterior end. It varies from 1 mm. on the 

 thinnest part of the sides to as much as 4 mm. near the cloacal 

 aperture ; and has the usual layers — cuticle, epidermis, con- 

 nective tissue, three muscle layers, and the lining of the coelo- 

 mic cavity. Under the epidermis there is a thick gelatinous 

 dermal layer (PI. 27, fig. 14, d., in which the green colour is 

 found), which may be up to 3 mm. in thickness. It is this layer 

 which gives rise to the variations in thickness of the body-wall. 

 The pigment is present in the form of accumulations of small 

 rounded masses (fig. 14, jo.). These may extend to the bases 

 of the epidermal cells, or even up between them, but always 

 belong to the dermis. Inside the gelatinous dermal layer 

 come the muscular layers of the body-wall, two circular layers 

 separated by a longitudinal, which are not broken up into 

 definite regularly arranged bundles as in the case of some 

 Gephyrea, but form a practically continuous layer of muscle- 

 fibres over the whole inner surface, becoming rather thicker 

 at the posterior end around the cloaca. Special muscle 

 bundles run in radial fashion from the wall of the cloaca to the 



