Correspondence — Prof. T. G. Bonney. 187 



to the same form as the mandible, and shows that the latter cannot 

 be referred to Machimosaurus. 



Aftei reviewing the whole of the evidence, the author concluded 

 that he was dealing with a Crocodilian allied to Metriorhynchus, but 

 forming the type of a new genus, to which he gave the name of 

 Suchodus, adding the specific name of durobrivensis. 



4. " On two new Species of Labyrinthodonts." By R. Lydekker, 

 Esq., B.A., F.G.S., etc. 



The right ramus of the lower jaw of a Labyrinthodont, from the 

 Lower Carboniferous of Gilmerton, near Edinburgh, is regarded as 

 referable to the Permian genus Macromerum, and it is proposed to 

 describe it as M. scoticum. 



Another mandible from the Karoo system of South Africa is 

 referred to the American Permian genus Eryops under the name 

 of E. Oweni. 



COEEESPOUDBUCB. 



THE CRYSTALLINE SCHISTS OF THE LEPONTINE ALPS. 



Sir, — To the abstract of my paper on " The Crystalline Schists 

 and their Relation to the Mesozoic Rocks in the Lepontine Alps," 

 read before the Geological Society on January 22nd, and reprinted in 

 the last Number of this Magazine, has been appended a long letter 

 written by Dr. Heim in anticipatory criticism, which was read during 

 the discussion. As the printing of that letter in extenso appears to me 

 to be a feature even more novel in your Magazine than it is in the 

 Abstracts of the Geological Society, I request space for the following 

 remarks : — 



1. I must leave to casuists more experienced than myself the task 

 of reconciling certain parts of that letter (as to what has been said 

 by Swiss geologists) with the paper, presented by Dr. Heim to 

 the International Geological Congress in 1888. After comparing 

 them, I can only put the old question, " What then does Dr. Heim 

 mean ? " 



2. The Carboniferous rocks of the Alps were only incidentally 

 mentioned in my paper. But I know something of these also, and 

 shall be surprised if it can be proved that any sedimentary rocks of 

 this age have been converted into true crystalline schists, or that the 

 " Calamite-like trunk from Guttanen" (which I have seen) occurs 

 in a gneiss. 



3. In regard to the "crystalline schistose rocks" of Mesozoic age, 

 in which it is stated that Belemnites occur with staurolites, garnets, 

 etc., — rocks which are now said not to be true crystalline schists — I 

 have only to remark that the whole aim of my paper was to show 

 that the rocks with garnet, staurolite, etc., were true crystalline 

 schists, that they were totally distinct from the schistose rocks with 

 fossils, that the former were below not above the (Triassic) rauch- 

 wacke, in which some of their members actually occur as frag- 

 ments, that the Belemnite-beariug rucks have only a superficial 



