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species of Martinia from the Iberger Ivalk, Upper Devonian of Grund, 

 Germany, with which he considered the species to be closely related. 



Ephippioceras. 



Ephippioceras ferratum, Hyatt. 



Nautilus ferratum, Owen (Geo/. Kentucky, iii, PI. x, Fig. 2). 

 Figs. 23-26, PI. x, enlarged 5 diameters. 



The nepionic stage is given in Fig. 23, from the side showing the 

 lateral longitudinal ridges of the paranepionic and part of the meta- 

 nepionic substage. These ridges are more acute on the venter and 

 wider apart and blunter on the sides. The form in section of the 

 metanepionic is digonal, and that of the paranepionic substage has 

 a more elevated venter and flatter dorsum. There was no dorsal 

 furrow in the paranepionic substage, so far as could be ascertained, 

 but the condition of the specimen left this fact open to doubt. 



It is interesting to note that the form and characters of the young 

 of this very aberrant form seem to indicate affinity with the Eudo- 

 ceratidse. 



The peculiar ridge-like mesal division of the septa, which corre- 

 late with the prominent ventral and dorsal saddles of this genus, are 

 not present in the nepionic stage. The imperfect condition of this 

 fossil did not enable me to make detailed observations upon the 

 young farther than in the stage figured. 



Trigonoceratidce. 



This family includes the close-coiled nautilian forms Coelonau- 

 tilus, Stroboceras, Apheleceras, Subclymenia and Diorugoceras. 

 The young of all of these genera, except possibly Diorugoceras, 

 which I have not seen and which is also very involute, have a simi- 

 lar history. They are rounded in the nepionic stage and have an 

 impressed zone only late in life, if they have it at all. Usually the 

 form is similar to that given in Figs. 29 and 30, PL x, of Apheleceras 

 mutabile (sp. D'Orb.), Hyatt. 



This species shows in the young that the genus has been but 

 recently derived from an arcuate type. The apex in the ananepi- 

 onic and part of the metanepionic substage is free and the whorls 

 barely touch at first. The corrugated shell of the nepionic and 

 neanic stages show also the same primitive characters and the resem- 

 blances of these younger stages to the loosely coiled gyroceran form 



