1893.] 61 



the much smaller Lac Brenet. And there is still a third lake (not 

 much more than a circular pond), known as Lac Ter, separated from 

 the large lake by an elevated narrow ridge, and of quite another 

 nature, filling a basin in a peaty hollow. 



For most Neuropterological purposes the defect of the country 

 is the scarcity of streams, torrents, and waterfalls, and the fact that 

 what large streams there are have the habit (not unknown in other 

 limestone districts) of running underground. 



Thus, a stream known as " La Lionne " has its source under- 

 ground, probably in the mountains, with an open-air course at 

 L'Abbaye on the Lac de Joux, of about a furlong, rushing out of the 

 face of a rock with sufficient volume and force to work powerful saw- 

 mills. Then again the Orbe, after feeding the Lac de Joux and Lac 

 Brenet, takes an underground course from the latter lake at a series 

 of funnels (" entonnoirs "),and re-appears three miles in distance, and 

 750 ft. in elevation, lower down, as a foaming torrent bursting out of 

 the base of a stupendous precipice 1000 ft. high, the spot being 

 known as the " Source de I'Orbe ;" but the actual source is far away.* 

 Up in the mountains there is no water in summer, save occasional 

 trickles after rain, and these are at once conducted into cattle troughs, 

 being too precious to be lost. 



The lakes produce quantities of fish ; " brocket " (pike) appeared 

 on the menu almost ad nauseam. The staple occupation of the inhabi- 

 tants immediately round the Lac de Joux is cheese-farming, and a 

 delicious gruyere is manufactured, the milk for which is produced by 

 a fine breed of cattle, large, well-fed, and scrupulously clean, a 

 contrast to some other Swiss districts. I am of opinion that a Lepi- 

 dopterist would be well satisfied with the district ; to a botanist it is 

 hardly necessary to allude to the richness of a calcareous soil at that 

 elevation. 



TRICHOPTERA. 



For Trichopterological purposes the district has three aspects, 

 viz. : — (1) the lakes ; (2) the streamlets, which are not numerous, and 

 of small size; (3) the "Source de I'Orbe." The most important is 

 undoubtedly the Source de I'Orbe, and to work this properly it is 

 necessary to stay at Vallorbe. I visited it for a few hours only on 

 two consecutive days, August 2nd and 3rd, and on the second occasion 



* There is considerable mystery regarding these lakes. It is said that the visible sources of 

 supply are quite inferior to the amount discharged at the entonnoirs, pointing to the possibility 

 of land springs at the bottom. As there is no other outlet, the district would be flooded should 

 any mishap occur to the erdonnoirs. It is also said that, notwithstanding the great difference in 

 the level, the water discharged takes many hours before it re-appears at the "Source," as 

 tested by the introduction of colouring matter. On these points the Guide Books give no 

 information. 



