THE GENUS HABROTROCHA. 633 



Kotifera which not only can endure life in the most exposed 

 situations, but which even seems to prefer it. It would be 

 difficult in Great Britain to find mosses growing in bleaker 

 places than on the tops of the Scottish and Welsh mountains, 

 yet wherever in such elevated places mosses can be found growing 

 and braving the storms, this species, sheltering in the moss-tuft-;, 

 seems able to flourish exeeedinsiv well. 



In many respects the new species Habrotrocha sylvestris is 

 closely allied to H. insignis, but the upper lip is not so high, and 

 lacks the curious stiffening so distinctive in the latter. On the 

 other hand H. sylvestris has a unique character of its own. In 

 certain Distylae (for example, D. depressa) the lower end of the 

 oesophagus (which seems to project into the stomach cavity) 

 has an incessant undulatory movement. I found a similar 

 movement of the oesophagus in H. sylvestris, where it has pro- 

 bablv some connection either with the formation of the food- 

 pellets or with their discharge into the stomach. 



Both H. insignis and H. sylvestris are probably of near relation- 

 ship to H. tridens (Milne), which, however. I judge, from the 

 description and figure given, to be an altogether more slender 

 and cylindrical animal than either. I have not been able to 

 identify it with certainty. 



The third species described, Habrotrocha pavida, is of quite a 

 different type, and is notable for its moderately wide corona, 

 and the bulging lateral margins of the mouth, which give it a 

 very characteristic outline when favourably seen. Although it 

 has been known to me for many years, it has, with one exception, 

 only been found in moss growing among the grass in a small 

 suburban garden. It is a very timid species, and will rarely 

 feed unless it is ensconced in a convenient ' heap ' of sand or 

 debris, from which it protrudes its head " at mealtimes." In 

 an earlier paper * I have described the manner in which the food- 

 pellets are moulded in the case of H. constricta (Dujardin). In 

 H. pavida there is a little more elaboration of the process. If a 

 good lateral view can be obtained while the animal is feeding, 

 the greater part of the oesophagus can be seen, albeit somewhat 

 indistinctly. The inner surface of the tube is apparently lined 

 with cilia, for there is an almost continuous undulatory move- 



* Bryce, " Further Xotes on Macrotrachelous Callidinae," Jourri. 

 Quek. Micr. Club., Vol. V., Ser. II., pp. 436-155. Xo. 35, 1894. 



