n8 HABITUDES AND ATTITUDES 



sedentary animals that require to be kept in 

 motion at the surface of the sea ; while the 

 hydroid is a sedentary species which requires an 

 adventitious mobility at the bottom of the sea. 



The Tubificidae are a family of small fresh- 

 water Annelid worms, allied to earthworms, which 

 live in the mud of water - courses, sometimes 

 occurring in almost pure cultures of innumer- 

 able individuals. They keep the head and 

 fore-body buried in the mud, whilst the hinder 

 portion of the body, through which respiration 

 is effected, is kept constantly waving as near 

 the surface of the shallow water as possible. 1 

 When alarmed, an entire colony will instantly 

 withdraw out of sight into the mud as with one 

 consent. Living in the same environment and 

 sometimes in company with the worms are to 

 be found the larvae of midge flies (Chironomus). 

 They have the same habit of waving the body 

 in the water and the respiratory processes occur 

 at the hinder end ; and, most singular coincidence 

 of all, the blood of the insect larvse is coloured 

 red with haemoglobin like that of the worms. 



In his description of the larva of Chironomus, 

 commonly called the " Blood-worm," Professor 

 Miall (" Natural History of Aquatic Insects," 

 London, 1895) says: "When undisturbed, they 



1 The habit of waving the posterior end of the body in the water 

 has been noted for Tubifex rivulorum by L. Atheston, Anat. Anz. f 

 xvi., p. 497 ; I have observed it in the case of an unnamed species 

 of Limnodrilus from Ceylon, as described in the text. 



