282 WILLIAM A. HASWELL. 



species (fig. 3) has a dark grey ground colour with rich brown 

 mottling. In the New South Wales species there are several, 

 usually three, broad transverse dark bands, separated from one 

 another by lighter intervals. In the middle of the most anterior 

 of these, towards its front edge, about a fifth of the total length 

 behind the base of the tentacles, is the dark spot on which the 

 eyes are situated, and in front of this is a lighter interval, 

 succeeded in front again by a dark space about the bases of the 

 tentacles; the latter are of a nearly uniform brown, rather 

 lighter towards the tips. Slightly behind the eyes, and rather 

 nearer the lateral margin than the middle line, there will be 

 seen on either side a minute white spot, which marks the posi- 

 tion of the opening of the excretory system. 



Little is to be seen of the internal organisation on a surface 

 view, the pigment of the integument being very dense. A few 

 light reticulating lines may be observed, which indicate the 

 position of the elements of the dorsal nerve-plexus, the ali- 

 mentary canal may be discerned as a lighter patch of squarish 

 outline towards the middle of the body, and a few, irregularly- 

 placed, fine transverse lines may be observed, which marks the 

 position of rudimentary intersegmental septa. 



On the ventral side the colour is light grey ; the sucker is 

 colourless. The squarish intestine, of a darker colour, is seen 

 through the body wall, and transverse divisions of its substance 

 indicate the intestinal pouches or caeca. 



Here and there among the full-grown Temnocephalee, in 

 the case of the larger New South Wales species, will be found 

 smaller immature specimens, distinguished by their whiteness ; 

 and when these are examined under the compressorium a good 

 deal is to be learnt regarding the internal organisation. They 

 are almost entirely devoid of pigment, except a little in the 

 neighbourhood of the eyes and along the back, and, strange to 

 say, they have invariably six tentacles, whereas the adult has 

 only five. 



When undisturbed the Ternnocephalse adhere to the sur- 

 face of the crayfish by means of the sucker, with the body 

 extended and inclined at an angle of about 45° to the surface 



