Correspondence — Prof. O. A. Lebour. 135 



stance of the shell having in all cases perished. The most perfect 

 of these hollow casts could not be distinguished from that of Denta- 

 lina communis, and I could venture to name other forms, but with 

 less certainty. 



As I am not aware that we have any recorded instances of Forami- 

 nifera of this modern t3^pe occurring so low down as the Lower 

 Silurian in Britain, though they have been found in rocks of this age 

 in Kussia, I think the fact of sufficient interest to be noticed, giAdng 

 us, as it does, so good an idea of the persistency of lowly-organized 

 life from specimens in our own countrj^ The slab is marked on the 

 other side with the tracks of Nereites Sedgwickei, and is now in the 

 Museum of the University College for Wales. 



Aberystwith, J. F. Blake. 



November, 1875. 



EANGE OF SACCAMMINA GART.ERI, BEADY. 



Sir, — If Mr. Bennie had read the note he quotes in its proper as- 

 sociation, I think he would not have written the letter which appears 

 in the January Number of the Geological Magazine, though we, its 

 readers, might thereby have lost a valuable contribution to our know- 

 ledge of the distribution of Saccammina. 



The text of my paper runs thus : " Nearly all the organisms 

 which it was supposed characterized the Yoredales in Northumber- 

 land have now been found in the lower beds of the Carboniferous 

 Series. . . ." Then comes the note : " Up to the present time, the 

 well-marked foraminifer Saccammina Carteri, Brady, is apparently 

 limited to a bed in the Upper or Yoredale part of the series, viz. 

 the Four-fathom Limestone." (Geol. Mag., 1875, Dec. II. Vol. II. 

 pp. 542, 54:3.) 



It will be seen that the words "in Northumberland " apply equally 

 to the note and to the text. And as Saccammina has never yet 

 been found out of the Four fathom Limestone in Northumberland, the 

 statement needs no correction. 



If Mr. Bennie will turn to page 329 of the '' Geological Eecord" 

 for 1874, he will see an abstract of Mr. Young's paper on Saccam- 

 mina, signed by myself. The explanation of Sheet 23 of the Geo- 

 logical Survey of Scotland has likewise been known to me ever since 

 its issue, and the localities for Saccammina duly noted. 



That the exact horizon of the Dunbar locality, which I had been 

 given to understand was considered as doubtful, has been satisfac- 

 torily determined, I am exceedingly glad to hear ; the more so as 

 perhaps the most remarkable specimen of the fossil in question 

 which has yet been found is one which was collected in that neigh- 

 bourhood many years ago by Mr. F. M. Balfour, of Trinity College, 

 Cambridge. 



Far from imagining, as Mr. Bennie seems to imply, that Saccam- 

 mina was limited to one horizon out of Northumberland, I have for 

 the last few years followed with great interest the almost daily in- 

 crease of its known range, both geographical and geological. 



I think that when Mr. Bennie sees the list of localities in which 



