Correspondence — Mr. F. J. Bennett. 379 



would be admissible. I certainly supposed that all students of 

 Lower Paleeozoic geology knew that the fossil which has been 

 determined as Trinucleus seticornis by Salter, Angelin, and many 

 others occurs abundantly in Middle Bala (Caradoc) beds. If Mr. Eeed 

 will turn to my Sedgwick Essay " On the Classification of the 

 Cambrian and Silurian Rocks" (published in 1883), where the 

 Upper Bala beds are generally separated from those of Middle Bala 

 age, he will find Trinucleus seticornis recorded as a Middle Bala 

 fossil in North Wales (p. 39), the Lake District (p. 67), and 

 Scandinavia (p. 76), and nowhere recorded in the Upper Bala list. 

 Mr. Roberts and I used the term T. seticornis beds locally because 

 we thought (wrongly it appears) that under the circumstances it 

 could mislead no one. 



In the above-mentioned discussion I disputed the statement that 

 T. seticornis was a characteristic Upper Bala fossil, as the form 

 which is usually taken as T. seticornis occurs, as remarked above, in 

 Middle Bala beds. I have not seen Hisinger's original specimen, 

 and have been unable to obtain access to a copy of the later (1840) 

 edition of " Letheea Suecica " in which the form is figured. If Mr. 

 Reed has examined Hisinger's specimen, and can prove that the 

 reference by Angelin, Salter, Linnarsson, Tornquist, Tullberg, and 

 others of the common Middle Bala form to Hisinger's species is 

 erroneous, I will cry " Peccavi." I am quite prepared to believe 

 that there is a characteristic Trinucleus in the Upper Bala beds, 

 but doubt whether it is Hisinger's species. I should not be surprised 

 if the variety Bucklandi, amongst others, be eventually proved 

 characteristic of these beds. 



There are many statements in the body of Mr. Reed's paper 

 on the Keisley Limestone with which 1 regret that I am unable to 

 agree, but I do not wish to trouble your readers with questions 

 ot detail, especially as I am given to understand that the fauna of 

 the Keisley Limestone is about to be examined by a very competent 

 palaeontologist. John E. Mare. 



Cambridge, July 15, 1897. 



ON THE OKIGIN OF LTNCHETS. 



Sir, — Mr. E. A. Walford's article, which attempts to give 

 a natural origin of lynchets, based on geological conditions, is not 

 very convincing, and seems indeed to refute itself. Had he seen 

 the many perfect examples which the Chalk Downs afford, I think 

 he would never have suggested a natural explanation for lynchets. 

 Joining the high road from Amesbury to Salisbury and close to the 

 Workhouse are some very typical lynchets, all in the Upper Chalk, 

 and yet confined to only a very small portion of it ; yet, if geologic 

 conditions are the cause, they should occur in many other localities 

 of the Chalk area. The opponents of the artificial origin must prove 

 why they are confined to small areas when the geologic conditions, 

 which they consider as the cause, occur over wide areas. 



Taking the Amesbury examples as typical ones, they will be seen 



