1863.] S0RBY MICA-SCHIST. 401 



minutely punctulatcd all over, but not striated : possibly one of the 

 Chrysomelidce (such as Oreina). 



3. A large uneven elytron, of a bright cyaneous blue, deeply 

 punctate-striated, and coarsely wrinkled transversely : possibly, from 

 its colour, a Chrysomela, though more probably, from its sculpture, 

 a large metallic Curculio ; apparently a common species. 



4. Elytron, scutellum, and prothorax, all partly visible. Elytra 

 gibbous, shining, sparingly punctured, but not striated, of the same 

 breadth at the base as the prothorax, but divided from it by a sharp 

 narrow suture ; scutellum very minute and triangular ; prothorax 

 more opaque, most closely and minutely alutaceous, with a longitu- 

 dinal depression on either side at its base : a small and rounded 

 Insect, like a very minute Cassida. 



5. A prothorax very evident, with an extremely broad, flattened, 

 and perhaps tubercled margin. The Insect is clearly elongate-oblong 

 and flat, though more convex and carinated down its central region : 

 either Cossyphus or Cassida ; I think decidedly the former. 



6. A large, bright, and more flattened elytron, finely, but simply, 

 or at the utmost subcrenately striated ; with the interstices most 

 minutely and sparingly punctured, and a little wrinkled. I think 

 Carabideous ; possibly a Licinus (or an allied genus). 



7. A large, uneven, but rather flattened elytron, distinctly cre- 

 nate- striated, and with the interstices most closely 'and coarsely 

 rugulose transversely, but not punctulated. Probably Carabideous. 



8. A long, rather narrow, and bright elytron, with the striae 

 excessively deep, sulciform, and impunctate ; the interstices almost 

 unsculptured, though most minutely alutaceous under a high power. 

 Apparently a rather large Insect. Possibly one of the JBiiprestida?. 



9. A bright cyaneous elytron, coarsely seriate-punctate, the punc- 

 tures large and remote, and with the interstices minutely rugulose : 

 most likely a Chrysomela. 



10. A small portion of an elytron, most coarsely, regularly, and 

 thickly tubercled or shagreened, but apparently without any other 

 sculpture. 



11. A large convex and polished elytron, most densely, regularly, 

 and minutely punctulated all over, but without any other sculpture : 

 I believe a Water-beetle. 



12. Possibly the fractured underside of No. 11. — T. V. W. 



2. On the Original Nature and Subsequent Alteration of 

 Mica-schist. By H. C. Sorby, Esq., E.R.S., E.G.S. 



That micaceous schists were originally deposited as sand and mud, 

 and that their present mineralogical and mechanical structure is due 

 to subsequent metamorphic action, may appear to some geologists so 

 thoroughly established as to make further proof needless. Since, how- 

 ever, some geologists in our own country and on the Continent have, 

 within the last few years, argued that the bands of varying mineral 

 character do not represent original stratification, but were due to 

 causes similar to those which have produced thin-bedded and almost 



