195 



Coregonus Ixicepedei was proposed for the one species, and that 

 of Coregonus microcephalus for the other, as illustrative of the spe- 

 cies. 



The Coregonus Lacepedei occasionally grows to the length of 

 sixteen inches, and is distinguished by the great length of head 

 compai'ed with that of the body ; the snout extending beyond the 

 upper lip ; the under jaw tlie shortest ; the length of the pectorals 

 and dorsal fin ; the large scales, the number of rays in the anal fin ; 

 the peculiar shape of the caudal, and the position of the dorsal. It 

 agrees in figure with Salmo Wortmanii of Bloch, but not in de- 

 scription. 



The Coregonus microcephalus does not grow to the size of the 

 last species, and differs from it in the liead and pectorals being 

 considerably shorter, and the snout not projecting .beyond the up- 

 per lip. It is at once removed from the vendace and pollan in the 

 under jaw being the shortest. On comparing it with the Gwyni- 

 ard, it is a much deeper fish, the head and pectorals much shorter ; 

 the upper jaw furnished with distinct teeth : anal fin with fewer 

 rays; besides it grows to a larger size than the Gwyniaad. 



These fish are found in Lochlomond in great numbers, where 

 they are named Powans or Freshwater Herrings, and are much 

 prized in that neighbourhood as being wholesome, well-flavoured 

 and delicate food, particularly during the autumn months. In the 

 stomachs of those examined vrerQ found several species of entomos- 

 tracious animals, larva of insects, a few coleoptera, and a number of 

 small tough red worms. They shed their spawn in the months of 

 October and November, after which they continue out of condition 

 till March. 



2. Abstract of Part II. of IMemoir descriptive and explana- 

 tory of the Mid Lothian and East Lothian Coal-fields. 



This part of the memoir was devoted exclusively to an attempt 

 to explain or account for the facts described in the first part of 

 the memoir. 



The geological epoch when the strata composing the coal-measures 

 of this district were deposited, was first noticed. It was stated 

 that these coal-measures were deposited at a period immediately 

 following the deposition of the old red sandstone formation ; and 

 that this older formation was to be seen both on the north and on 

 the south sides of the Lammerrauir Hills, dipping under the coal- 

 measares, and resting on the upturned greywacke strata of these 



