13^ The Irish Naturalist. June. 



to be found : there is a table giving succinct descriptions of the dis- 

 tinguishing qualities of each, and of the eggs they should contain; and 

 the coloured plates give good representations of the eggs of 37 species (all 

 passerine), selected as those which the author considers to be the " most 

 generallv confused." There are also a number of photographs, but it 

 can hardly be said that these are intended to assist identification. Their 

 object is rather to stimulate the young naturalist to "go and do like- 

 wise." As there is so much diversity of temperament among young 

 people one hesitates to say a word in disparagement of Mr. Sedgwick's 

 mode of appealing to them, which will doubtless be effective in some 

 quarters ; but we are inclined to think that identifications made in the 

 hurried manner that this book aims at promoting will not leave a very 

 abiding impression on the memory. We would prefer recommending a 

 book of moderate dimensions that can be left at home, that does not 

 make a point of disregarding classification and "technical or Latin 

 names," and whose zeal for brevity is not carried to the excess of leaving 

 us to distinguish a swallow's nest from a House-martin's by the single 

 criterion of its greater untidiness. C. B. M. 



e>' 



THE SURVEY OF THE DERRY DISTRICT. 



The Geology of the Country around Londonderry. By S. B. 



Wii^KiNsON, A. M'Henry, M.R.I. a., J. R. K11.R0E, A.R.C.Sc.L, 



and H. J. Skymour, B.A., F.G.S. (Memoirs of the Geological Survey 



of Ireland). Pp. 106, coloured map, 7 plates and 11 text-figures. 



Dublin : H. M. Stationery Office, 1909 Price 2s. 



In pursuance of the plan adopted by the Irish Geological Survey, of 



presenting the large centres of population wdth a map accompanied by 



a memoir, in which a detailed account of the physical features and the 



geological structure of the surrounding country is given, the fifth of an 



interesting series of memoirs has been published. 



The map is composite, containing portions of 4 one-inch sheets — 11, 

 12, 17 and i8. It is of the usual size 18" x 12 ", and thus embraces an 

 area of 216 sq. miles, at about the middle of which the city stands. 



Part I., Section I., refers to the Physical Geograph}' of the area, and 

 here the origin of the Promontory of " Inishowen," literally Owen's 

 Island, is discussed. Professor Hull's opinion that "within the historic, 

 or at least, traditionary period, it may have been really an island, at least 

 during high tides," is commented upon. A subsidence of 20 feet would 

 allow the sea to flow over most of the low tract between Loughs Foyle 

 and Swilly, along which the railway to Buncrana now runs, whilst a 

 lurther reduction of level by 30 feet would convert Inishowen into an 

 island once more. In discussiug the Foyle and Burngibbagh valleys, 

 which preserve a distinct parallelism for 12 miles, Mr. Kilroe concludes 

 that the Burngibbagh was originally the principal stream, whose 

 head waters were captured by the Foyle long before the Glacial Epoch. 

 Fincairn Glen, 3 miles E. of the city, is an example of a dr>' gap. It 

 extends for two-thirds of a mile, and is about 100 feet deep, with 

 precipitous walls of rock. The frontispiece gives a view of the north 

 end, with a delta fan formed by the river which now occupies the glen 



