Hyatt.] 288 [April 4, 



Edaphoceras, 1 nobis, includes species with the young arcuate 

 until a late stage of growth, with whorls fusiform in section, and 

 sutures with dorsal, and ventral lobes, and angular lateral saddles 

 as in adults of Eudoceras, but the siphon shifts from the venter, 

 where it is in the larva, to near the centre. Unfortunately the 

 only figured species is the Edaph. (Tern.) niotense, M. et W. Geol. 

 111. Vol. 5, pi. 19. This is selected as the type because it is 

 figured, though in our opinion it is not a full grown shell but only 

 the later adolescent stage of a species as yet undescribed in the 

 collection of Mus. Comp. Zool. The adult in this is close coiled, 

 with flattened sides, broad lateral saddles. An impressed zone 

 appears on the dorsum due to close coiling altering the form in 

 section from fusiform to kidney-shaped, and a V-shaped annular 

 lobe appears in the middle of the broad dorsal lobe. 



Endolobus, M. et W. Geol. 111., Vol. 2, pi. 25, p. 307. End 

 (Naut.) Avonensis, sp. Dawson, has all the young stages like the 

 preceding genus, but inherits the annular lobes, shifts the position 

 of the siphon to near the centre, acquires the impressed zone, and 

 changes the form of the whorl to the kidney shape at an earliet 

 stage of the growth. The young have broad ventral lobes, bur 

 the adults develop saddles in the centre of these, and in the 

 type, End., spectabilis, large folds or tubercles appear on the 

 sides. The latest survivor of this series is the End. (Naut.) exca- 

 vatum sp. D. Orb. of the Jura, Terr. Jurass. Ceph. pi. 30. 



Gonioceratidae. 



We interpolate this extraordinary group here because its near- 

 est affines are the compressed, straight cones with equal dorsal 

 and ventral sides. This relationship is fully appreciated by Pro- 

 fessor Hall who considers his genus Eudoceras as very closely 

 allied to Gonioceras. 



Gonioceras, Hall, Nat, Hist. N". Y. Vol. 1, p. 54 has a broad 

 winged shell, which in form and structure, as indicated by the 

 septa and striae of growth, closely resembles the internal shells 

 of Sepia. We think, the facts are sufficient to warrant our as- 

 suming this, as probably one of the passage forms from the 

 compressed Orthoceratites, above described, to the true Sepioidea, 

 and possibly a more or less remote ally of Paleoteuthis Dunensis 

 Roem. of the Devonian. 



i "E8cuJ>os, a seat. 



