302 TRANSACTIONS, NATURAL HISTORY SOCIETY OP GLASGOW. 



Mr. Peter Macnair, F.K.S.E., F.G.S., read a paper on "The 

 Fish Fauna of the Upper Silurian Inlier of Lesmahagow." He 

 referred to the geological features of the ground, and showed that 

 the rocks had been folded into :i dome-shaped anticline which 

 I'ougiily coincided with Nutberry Hill. In the centre of the hill 

 occurred the oldest rocks, which are of Wenlock age, and these 

 passed upwards into a thick group of sandstones, mudstones, and 

 conglomerates of Ludlow and Downtonian age. The first 

 announcement of the existence of Upper Silurian fossils north of 

 the Tweed was made in 1855 by the late Dr. Slimon of 

 Lesmahagow. Within recent years, a remarkable group of fishes 

 was discovered in these rocks, by means of which Dr. Traquair 

 has been enabled to throw a Hood of light upon the origin and 

 descent of that highly problematical group of fishes known as 

 the " Ostracodermi " or armour-plated fishes. A considerable 

 diversity of opinion has always existed regarding the zoological 

 affinities of these organisms, they having been referred by some 

 to the Arthropoda and by otliers to the Tunicata. Dr. Traquair, 

 in a series of valuable memoirs, has shown that the fishes from 

 the Upper Silurian rocks of Lesmahagow are probably primitive 

 Elasmobranchs, and that they supply the ancestral forms from 

 which the highly specialized armour-plated fishes were descended 

 through the Psammosteid and Drepanaspid types. Many 

 specimens of Thelodus, Lanarkia, Birkeiiia, Lausanius, and 

 Fsammosteus were exhibited in illustration of tiie paper. 



Mr. Robert Henderson submitted a List of Additions to the 

 Diptera of the Clyde Faunal Area (page 156), being the third paper 

 communicated by him on that subject.* It records the species 

 belonging to the families from Anthomyidse to Hippoboscidse 

 whose occurrence he has observed in the Clyde Area, together 

 with a few unrecorded species belonging to families dealt with in 

 his two former lists. Altogether, in this third paper, he is able 

 to record in these families 308 species, of which 215 are 

 additional to the list of Diptera published in the British 

 Association Handbook of 1901. Many of these species are not 

 yet on our recognised British List, and are but little known. In 

 the course of some remarks on the increasing attention now being 



* See Transactions, vol. vii., p. 148 ; vol. viii., p. 7. 



