1894- NOTES AND COMMENTS. 255 



brackish to either fresh or salt waters. By Gray and DesmouHns 

 this genus was referred to Mactridae, while the fact that in certain 

 features it recalled Cyrenidae was duly recorded. Fischer, in his 

 " Manuel," under the synonym of Rangia, places it next to Cyrenidae, 

 at the same time raising it to family rank. A careful examination of 

 the animal, however, has convinced Dr. Dall that the earlier 

 naturalists were right, and the genus must be classed with the 

 Mactridae. Six genuine and six spurious or doubtful species are 

 recorded in this monograph, which appears in the Proceedings of the 

 U.S. National Museum, xvii., pp. 89-106; i pi. 



Mr. R. W. Chapman and Captain Inglis are continuing their 

 valuable observations on the tides of Port Adelaide, South Australia, 

 and we have just received their brief report presented to last year's 

 meeting of the Australasian Association. At that time they were 

 proceeding with a second analysis of the Port Adelaide curves, with 

 the aid of Professor G. H. Darwin's computing apparatus. 



The lake formed a year ago by the great landslip at Gohna in 

 the Himalaya, burst through its dam at the end of August, and thus 

 has terminated one of the most gigantic geological catastrophes of 

 recent years. Mr. T. H. Holland, of the Indian Geological Survey, 

 has favoured us with a copy of his detailed illustrated report {Rec. 

 Geol. Surv. India, vol. xxvii., pp. 55-65, with 5 plates and 2 maps), 

 and from it we learn that the slip was due to the ordinary cause. 

 The rocks on the side of the valley which collapsed dipped at a high 

 angle towards the valley, and the landslip naturally followed heavy 

 rains. On a small scale, as Mr. Holland points out, such valleys as 

 that of Cheddar illustrate the same principle ; the side on which the 

 rocks dip towards the valley has a very gentle, stable slope, while 

 the opposite side stands equally firm as a great precipice. 



We are informed that a boring for coal will shortly be under- 

 taken in the valley of the Stour. At .a meeting held in Ipswich on 

 the 28th August, the Chairman of the Directors (Mr. R. C. Napier) 

 intimated that over ;^5,ooo had been promised, so that there was no 

 reason for further delay. It will be remembered that slaty rocks, 

 older than Coal-measures, but of Carboniferous age, have been pierced 

 at Harwich, and it is considered likely that coal basins may occur ia 

 the folds of the old rocks between the east coast and London. 



Geologists of the rising school are continually attacking the 

 orthodox theory of the origin of coal-seams ; and it is quite Hkely they 

 are correct in most cases, though the exceptions to the rule of growth 

 in situ are never proved to be more than local. Another contribution 



