TRANSACTIONS OF SECTION C. 725 



teeth, somewhat like a shoe-last in form, which played upon strong, flattened, bony- 

 plates that covered the roof of the mouth. These, like Diploynathus, are from the 

 Huron shale of Ohio. 



5. Ctenodus Wagneri, Newb, of which a remarkably large and finely preserved 

 palate tooth was exhibited, discovered by Mr. Frank Wagner in the Cleveland 

 shale near the base of the Carboniferous system at Cleveland, Ohio. 



6. Spines of two species of Edestus, Leidy, from the Coal Measures of Indiana 

 and Illinois, which show distinctly the structure and mode of growth of these re- 

 markable defensive weapons. They are from 10 to 18 inches in length, very 

 massive and strong, and consist of a series of sheathing segments firmly soldered 

 together, each carrying a triangular, crenulated, and enamelled denticle from 1 to 2 

 inches in length. The spines are symmetrical and were therefore located on the 

 median line like the spines of Tryyon, and were probably the defences of large 

 sharks or rays which inhabited the inland waters of the Continent in the Carboni- 

 ferous a<re. 



SATURDAY, AUGUST 30. 

 The Section did not meet. 



MONDAY, SE PI EMBER 1. 



The following Papers and Report were read : — 



1. On the Fossil Reticulate Sponges constituting the Family Dictyospongidoz. 

 By Professor James Hall, LL.D. 



. Our knowledge of these forms in America dates back to 1842, when Mr. 

 ' 'onrad described a peculiar fossil body under the name Hydnoceras (in the belief 

 of its relation to Orthoceras). Subsequently in the same year another form by 

 Vanuxem as a marine plant, and in 1862 Dawson as Algae, and followed by Hall 

 in 1863, who described several of the species under the name Dictyophyton ; adopt- 

 ing Vanuxem's name Uphantaenia for other forms. 



In 1879 Mr. C. D. Walcott described a form referable to this group of fossils, 

 from the Utica State, as Cyathophycus. In 1881 Mr. R. P. Whitfield published 

 observations on the structure of Dictyophyton and its affinities with certain sponges, 

 accompanied by a note from Dr. J. W. Dawson, on the structure of a specimen of 

 Uphantpenia, &c. (D. Walcott on the Nature of Cyathophycus.) 



In the same year R. P. Whitfield (with note by Dr. J. W. Dawson) described 

 two species of Dictyophyton and one of Uphantosnia. (Bulletin of the American 

 Museum of Natural History.) 



In 1882, James Hall upon Dictyophyton, Phragmodictya, and similar forms 

 with Uphantaenia. (American Association for the Advancement of Science.) 



In the European literature, the first notice of which was observed by the writer, 

 of any fossil resembling Dictyophyton, is in Murchison's Silurian System (1839), 

 where C'ophinits dubius is described and figured. 



(In Morris' Catalogue this fossil is placed in the category of incertce sedes.) 



In 1845, Mr. Coy, in his ' Synopsis of British Palaeogoric Fossils,' describes 

 Tetragonis Danbyi {Iteceptaculites Danbyi, Salter in MS.) 



In 1874 (43) Mr. Salter, in his Catalogue of the Cambrian and Silurian Fossils 

 in the Cambridge Museum, places Tetragonis Danbyi under the Spongidae. 



In 1880, Dr. Ferdinand Roemer has described the genera Dictyophyton and 

 Uphantaenia (Lethea geog. Thiel, p. 126 and 128), placing them among the Algae. 

 At a later date the same author places Tetragonis Murchisoni, T. Danbyi, and T. 

 Eifelemis among the Spongidae. 



