THE ENICOCERT. 257 



surface of the water. In this respect these insects differ from 

 the alHeJ genus, Elniis, whose favourite resort is the under side 

 of rough stones, apparently preferring such as are in the most 

 rapid parts of the brooks, and that side of the stone exposed 

 to the force of the stream. In the Wansbeck they were in 

 the greatest profusion in August. I have also taken them at 

 various places near Newcastle, in October and April, and doubt 

 not they may be met with most months of the year, though 

 autumn and winter must be considered their principal season. 

 I am borne out in this supposition by the fact of having gene- 

 rally observed the larvae and pupae in company with the perfect 

 insect, especially in the autumn. The former (larvae) are 

 anopluriform, measuring, when full grown, about two and a 

 half lines in length, and half a line in width. They are of an 

 uniform black, and have the apex of each abdominal segment 

 fringed with very short hairs. Their food is most probably 

 mucor, for they seem to be confined to the rough slimy stones ; 

 and I find that it is quite as great a waste of time to look for 

 them on a smooth limestone, as to turn up a fragment of 

 basaltic rock (vulg. whinsto?ie) in search of Geodephaga.^ 

 When full grown, the larvae leave the water, and crawl up the 

 sides of the stone in search of a convenient place in which to 

 undergo ^ their change. After a long journey of frequently 



a The apparent repugnance of beetles to basalt I have long noticed. Two or 

 three years ago I lost a day or two in June entomologizing in Teesdale, — so far 

 at least as my cabinet was concerned. The subjacent rock of this wild district 

 is almost exclusively composed of the basalt of the great Whin Sill, whose 

 formation is so knotty a point with geologists ; and of course the loose stones of 

 the surrounding country are its fragments. Botanists have made its treasures 

 known far and wide ; and though I found the exquisite Gentiana verna, and the 

 equally rare, though sombre, Bartsia alpina in some plenty, I scarce saw a single 

 beetle, notwithstanding I turned over multitudes of likely-looking stones, and even 

 they were such as are superlatively common elsewhere, though here "inter 

 rariores." So far as my observations, whether confined to single stones or 

 extended over a whole district, go, any place having limestone, particularly the 

 magnesian, for its subjacent stratum, will afford abundance of the Geodephaga as 

 well as most other Coleoptera, whilst they will be found very thinly scattered 

 over a basaltic region. It is strange to notice the almost uniform absence of 

 these insects on turning up a Whin which has accidentally found its way into a 

 heap of any other stones, though every one of the latter may have one or more 

 tenants under it. Must we not look to the comparative dryness of the limestone 

 and humidity of the Whin for an explanation ? We can readily account for the 

 great predominance of the land Testncea on a limestone district ; but lime does 

 not enter into the composition of beetles. 

 NO. III. VOL. I. L L 



