Correspondence — Mr. G. C. Crick. 93 



adit levels. The change of colour in Llydaw explains the colour of 

 Glaslyn, about the cause of which there has hitherto been some 

 doubt, for it must now be obvious that Glasl^ai owes its green colour 

 to the detritus of green rock washed into t from the adit levels of 

 the mine. J. K. Dakyns. 



Pen-y-Gwryd, Nov. 14, 1899. 



CATALOGUE OP THE^FOSSIL CEPHALOPODA IN THE BRITISH 

 MUSEUM (NATUEAL HISTORY), PART III : A CORRECTION. 



Sir, — The woodblocks used in illusti'ating Part iii of the " Cata- 

 logue of the Fossil Cephalopoda in the British Museum (Natural 

 History)," by Dr. A. H. Foord and myself, have just passed through 

 my hands, and on comparing them with the figures in the book 

 I find that there has been a very unfortunate transposition of the 

 figures of the suture-lines of some of the species of Gephyroceras. 

 The blocks themselves are numbered correctly, but owing to 

 a printer's error they do not appear in their proper places in the 

 volume. The following corrections are necessary : — For Fig. 33 

 (suture-line of Qephtj racer as affine) see Fig. 34 : for Fig. 34 (suture- 

 line of Gephyroceras calculiforme) see Fig. 36 ; for Fig. 35 (suture- 

 line of Gephyroceras cequahile) see Fig. 33 ; and for Fig. 36 (suture- 

 line of Gephyroceras serratum) see Fig. 35. These four figures, then, 

 with their descriptions, should have been as follows : — 



Fig. 33. 



t 



Suture-line of Gephyroceras affine (Steininger), Copied from Holzapfel and completed. 



Fig. 34. 



Suture-line of Gephyroceras calculiforme (Beyrich), enlarged. After Sandberger. 



FiQ. 35. 



Suture-line of Gephyroceras cequahile (Beyrich). After Sandberger. 

 Fig. 36. 



Suture-line of Gephyroceras serratum (Steininger). After Sandberger. 



Geo. C. Crick. 

 British Museum (Natural History). 

 December 22, 1899. 



