456 TRANSACTIONS LIVERPOOL BIOLOGICAL SOCIETY. 



neighbourhood of Port Erin but to be nowhere very 

 abundant. It has been obtained from the shore at Port 

 Erin and Perwick where it inhabits the smaller weeds on 

 reefs and in rockpools, and has also been dredged on 

 shelly ground in about 15 fathoms. All the specimens 

 taken were small, varying in length from 6 to 12 mm. 

 No mature individuals were met with, one immature 

 female being the only specimen in which genital organs 

 were observed. 



In addition to the other well marked characters of this , 

 species, the relative shortness of the proboscis may be 

 noted. This organ extends back barely half the length of 

 the body from the anterior end. 



The colour of the Port Erin examples varied from 

 peach-colour to fairly bright orange red, and being due 

 almost entirely to the alimentary tract was much more 

 marked in the posterior half of the body. The fluid in the 

 proboscis-sheath had in some cases a pale yellow tint, as 

 had also the blood vessels in some specimens, more 

 especially in the posterior region of the body. 

 Tetrastemma dor sale (Abildgaard). 



Two well marked colour varieties were found, apparently 

 restricted to different habitats. 



The common dark brown type marbled with irregular 

 patches of reddish brown — narrow but of dark colour 

 where they cross the pale median dorsal band, widening 

 out but becoming paler on the sides of the body — is com- 

 monly found on the shore and in the Laminarian zone, 

 but does not appear to extend into the deeper water 

 outside. At all events on the shelly ground in 15 — 20 

 fathoms a much paler form of a brownish yellow colour 

 was exclusively found. In the absence of much superficial 

 pigment, the colour in these was due largely to the 

 alimentary tract. Some examples had hardly a trace of 



