FOSSILS OF THF CLINTON GROUP. 537 



Repeated examination of the type of Glyplodendron Eatonense Clay- 

 pole has led to the conclusion that our species was not distinct from 

 that form. The Eaton specimen possesses the same ridge defining 

 the lower border of the figures. To be sure the figures in Glyploden- 

 dron Ealonense have a greater height compared with their breadth than 

 our specimens, but it has been noticed in the Huffman Quarry specimen 

 that the relative heights of the markings increase towards the outer or 

 convex side of the coil. The Eaton specimen is therefore regarded as a 

 cast of the surface of the outer side of the shell, where it is convexly 

 bent. The general contour of the figure is preserved, but the finer mark- 

 ings are gone. The type specimen was described from the Clinton near 

 Eaton, Ohio, Geol. Mag. Dec. II, Vol V, London, 1878. Further discus- 

 sion may be found in the Amerian Geologist, loc. cit. The writer here 

 acknowledges the repeated generosity and courtesy shown him by Prof. 

 E. W. Claypole in the use of this and other specimens, and for all 

 information desired in connection with this and other geological subjects. 



Recently a large Cyrtoceras fragment has been found in the upper 

 shaly courses at Huffman's Quarry, having a diameter of 150 mm. It 

 includes 4 chambers, the total height of which toward the middle is 60 

 mm. The siphuncle was large, the segments are much contracted at the 

 septa, and are very oblique. They are 26 mm. in width in a direction 

 parallel to the septa, and 20 mm. high in a direction perpendicular to 

 that surface. A certain amount of compression has evidently also taken 

 place. 



The ornamentation of the two species here described is so remarka- 

 ble that the subgeneric designation, Glyptoceras, may be valuable for 

 distinguishing this class of species from the more ordinary types. 



Orthoceras {Actinoceras) Youngi, Foerste. 



(Plate 33, Fig. 3; P. ate 36, Fig. 1.) 



The type specimen was found at Hanover, Indiana, (Proc. Boston 

 Soc. Nat. Hist., 1889). Recently three magnificent specimens were 

 obtained from the "Orthoceras block" at Huffman's Quarry. These ena- 

 ble us to give a much better description of the same. Of these the finest 

 was 190 mm. long; at its larger end it was 63 mm. in diameter, and at its 

 smaller end 31.5 mm. At its larger end 10 septa occurred in a length of 

 57 mm. In a second specimen of about the same length, the siphuncle was 

 seen to be distinctly contracted toward the septa, securing thus a structure 

 which may be compared to a string of large beads in which however the 

 beads join each other closely. There where the shell had a diameter of 

 66 mm. the siphuncle had aunulations 9.5 mm. wide. Where the diame- 

 ter of the shell was only 32.5 mm., the siphuncle had annulations 7 mm. 

 wide. The two points chosen for measurement were about 195 mm. apart. 

 The connection between the annulations was 7 mm. and 4.2 mm. 



