684 



narrow lanceolate, the inner broad at the base and sharply contracted 

 at the apex. 



Colour white. Length (of largest specimen] 7,5 mm. 



The above description has been prepared from three specimens only, 

 possibly not fully mature, so that it is probably imperfect in some respects. 

 However I think there is no doubt that the species is distinct from any 

 hitherto described. 



These specimens were found on Feb. 23. 1906 hidden beneath 

 stones at the mouth of the spring known as Aïn el-Hadjar about 10 km 

 west of Biskra. This spring rises from a calcareous rock at a tempera- 

 ture of 27° C, with an output of 1800 litres a minute. The water is per- 

 fectly clear, rather sulphurous to taste and smell, but quite potable. 

 This is one of several springs whose water, collected in a narrow arti- 

 ficial channel, supplies the Oasis of Oumach about 12 kilometres to the 

 South East. 



The species is evidently of subterranean origin and is of great 



Fiff. 4. 



Fi^. 5. 



Fig. 4. Mandible. X 65. 



Fig. 5. A Leg of the first pair. X 25. 



interest as belonging to a group which is most characteristically marine. 

 The close relationship existing between many subterranean Crustacea 

 and certain marine and sometimes deep-sea, forms has been noticed by 

 several authors, and it has been supposed that the subterranean Crusta- 

 cean fauna has been derived, not so much from the surface, as directly 

 from the sea itself. The discovery, in recent years, in spring waters, of 

 such obviously marine forms as Cirolana cuhensis Hay, Typhlocirolana 

 moraguesi Racovitza, Cirolanides texanus Benedict etc. lends much 

 support to this view. Such a direct origin from the sea does not seem 

 to present any insuperable difficulties. There must, in many cases, be 

 submarine access to the outflow of subterranean water, and it seems to 

 be still undecided whether the so-called tidal wells of Australia and 



