Oeohgy and Mineralogy. 411 



Cahaba field at 230 square miles, the average thickness of worka- 

 ble coal over the entire field would probably scarcely attain fifteen 

 feet. This estimate, so much lower than we have been accustomed 

 to see stated in reports and newspaper articles, is probably not 

 very different from the thickness which the same method of esti- 

 mating would give for any of our other bituminous coal fields. 

 " The enormous thickness of the coal-bearing rocks in the Cahaba 

 field, being estimated at over 5,000 feet, has no parallel in the 

 Warrior coal-field." Record of four borings in the Warrior field 

 show sections of from 400 to 600 feet of strata, including four, 

 seven and eleven coal-horizons. 



Prof. Lesquereux furnishes a list of 57 species of coal-plants, (of 

 which 12 are named as new,) and remarks upon the veiylow posi- 

 tion in the Coal-measure series to which they must theoretically be 

 assigued, a few species, such as Sternbergia, Lepidodendron Wei- 

 theimianum and AsterophylUtes gracilis, ranging down even into 

 the Devonian. This corresponds with the suggestions already 

 made, by several geologists, that the coal-measures of the Southern 

 States are all very low in the series, the whole having been called 

 '* Bub-conglomerate " by some writers. We should prefer, how- 

 ever, some more certain evidence on this point than has yet been 

 produced. The surveys of Alabama, Georgia and Kentucky, now 

 m progress, will leave but a short gap (in northern Tennessee) 

 between the well-known fields of Pennsylvania and Ohio and the 

 southern extremity of the system. 



The body of the report is occupied with details of County-work, 

 mostly in the Silurian areas of the State. Some analyses of ores 

 are given, besides lists of elevations. There is also a valuable 

 paper by A. R. Grote, on the cotton-worm {Aktia argillacea 

 Hiibner) which is preliminary, the author states, to a more ex- 

 tended history of the worm. Mr. Grote writes from observations 

 in Alabama on the habits of the worm, and also from a study of 

 it elsewhere. He is an excellent entomologist, and if his reviews 

 are continued in the survey, will add greatfy, by his study of the 

 insects injurious and beneficial, to the value of the State Reports. 

 We understand that the State approjjriation, for the work thus 

 reported on, is only $500 a year to cover the travelling expenses 

 of the geologist during the vacations of the State University, in 

 which institution he is a Professor. The volume may therefore 

 properly be accounted a personal contribution to the cause of 

 science. 



4. The Geological Record for 1874.— An account of works on 

 Geology, Mineralogy and Pahieontology, published dunng the 

 year. Edited by William W^hitaker, B.A., F.G.S., of the Geo- 

 logical Survey of England. 398 pp. 8vo. London, 1875. (Taylor 

 & Francis.)— Mr. Whitaker, the editor of the Geological Record, 

 has had able co-workers, and has produced a volume which will be 

 found of great value to all of all lands that are interested in the 

 progress of geological science. The sub-editors are the follow- 

 ing, all members of the Geological Society : W. Topley, G. A. 



