342 [Proc. B.N.F.C. 



Hyndnian, and Patterson. These three indefatigable workers 

 left records of 391 species of shells, both living and dead, 

 found by them in our waters.. He then pointed out the 

 position of the mollusca in the animal kingdom, and 

 divided them into their orders, according to their well- 

 known characters, after which he referred to each family 

 of the orders inhabiting our local waters, and pointed out 

 their well-marked and easily-recognised differences, enume- 

 rating all the species. Mr. Donaldson's lecture was well 

 attended, and the discussion which followed showed the sub- 

 ject to be still full of interest. The lecturer illustrated his 

 remarks by a large array of specimens kindly lent by the 

 Museum authorities for the purpose. 



GEOLOGICAL PHOTOGRAPHS. 



On 29th March the concluding weekly meeting of the 

 Winter Session was held in the Club-room at the Museum in 

 College Square — the President, Mr. W. J. Fennell, M R.I.A., 

 presiding. There was a large attendance, due to the attractive- 

 ness of the subject announced and the popularity of the lec- 

 turer, Mr. R. Welch, M.R.I.A., who chose for his subject 

 the new drift survey of the Dublin, Belfast, and Cork areas, 

 with special reference to the photographs taken to illustrate 

 the geological memoirs which describe the areas mapped. The 

 old memoirs were illustrated merely by rough woodcuts, 

 helped out by line blocks. In the new memoirs carefully 

 printed half-tone blocks from photographs are used instead. 

 All the photographs taken were exhibited, and the more 

 interesting ones in each area pointed out. Among these were 

 the dry gap in the Dublin Hills known as Dingle, a puzzling 

 ravine, which seems to have been formed during the melting 

 of the ice in late glacial times, the sections in the Greenhills 

 esker, and the crushed slates at Howth Head; in the Belfast 

 area, sections in the deposits of the ancient Lake Belfast 

 were shown, and the volcanic sills at Scrabo Hill; in Cork, 

 those curious submerged pre-glacial river gorges, which cut 

 across the old red sandstone ridges and the pre-glacial raised 



