Geology and Mineralogy. 315 



Wis. ; and the Schultze collection in the Museum of Comparative 

 Zoology containing European fish remains. The species described 

 belong to the genera JPtyctodus Pander, Rhynchodus Newberry, 

 Palceomylus Woodward, and ichthyodorulites are described under 

 the new generic names Phlyctcenacanthus and Belemnacanthus. 



The stratigraphic relations of the fish remains and their asso- 

 ciation with invertebrate fossils lead the author to agree with the 

 general conclusions of Stuart Weller regarding the relation of the 

 Milwaukee beds to the New York and Iowa faunas. 



"The Chimaeroids give it (the hydraulic limestone of Mil- 

 waukee) a stamp of antiquity, suggesting that a westward migra- 

 tion took place during the early part of the Devonian as far as 

 Wisconsin, but not crossing the Mississippi Valley until the 

 Middle Devonian. The Milwaukee beds show the first traces of 

 the encroachment from the East, the Rock Island locality a some- 

 what later, and the state quarry limestone the last of all, with its 

 horde of Upper Devonian lung-fishes." 



The second paper gives a critical comparative study of the 

 cranial osteology of the Dinichthyids, with a particular descrip- 

 tion of an early type, D. pustulosus Eastman, based upon speci- 

 mens from the Milwaukee and Iowa localities. The author 

 considers this species to be the most primitive member of the 

 genus known. His studies lead him to regard Coccosteus and 

 Titanichthys as the extreme limits of the family Coccosteidse, 

 with Dinichthys as an intermediate and connecting link. Speak- 

 ing of the Dinichthyids the author says : " But when their char- 

 acters shall have been fully investigated, the wide range of 

 variation manifested by them will be found reducible to order, 

 and the whole promises to constitute one of the most interesting 

 evolutionary series known among fossil fishes " (p. 747). 



h. s. w. 



2. Geological Sketch of Sail Clemente Island ; by W. S. T. 

 Smith. Extr., 18th Ann. Rept., U. S. Geol. Survey, 1896-97, 

 Part II, pp. 459-496, plates lxxxiv-xcvi, figs. 82-85. 1898.— San 

 Clemente is the southernmost island of the " channel islands " off 

 the southern coast of California. The island has been described 

 as a " tilted orographic block " by Lawson. The rocks are chiefly 

 volcanic. The oldest sedimentaries are of Miocene age. The 

 author recognizing this as a typical fault block, and isolated from 

 other land masses, the topography of which is still in its infancy, 

 has presented a theory as to the development of its drainage. He 

 also describes the structural and petrographic features of the vol- 

 canics, and a general description of the sedimentaries, moraines and 

 later deposits. h. s. w. 



3. Geology of the Edwards plateau and Rio Grande plain, etc.; 

 by Robert T. Hill and T. Waylaid Vaughan. Extr., 18th 

 Ann. Rept., U. S. Geol. Survey, 1896-7, Part II; pp. 193-321, 

 plates xxi-lxiv, figs. 53-76. 1898. — The geological features of 

 the region from Austin, Texas, westerly and southwesterly 

 through San Antonio to the Rio Grande, are described and beauti- 



