416 REPORT ON THE STATE CABINET. 



some specimens, had tlie parts been at all shelly in texture. At least 

 one other species in the same formation preserves a similar feature in 

 the siphuncle. 



Formation and Locality. — In limestone of the age of the Niagara group, 

 at Racine, Wisconsin. 



Orthoceras niagarense, n. s. 



PLATE XX, FIG. 8. 



Shell elongate, gradually tapering; section broadly elliptical; septa 

 deeply concave, depth of chamber about five lines where the 

 diameter is one and a half inches ; siphuncle eccentric. Surface 

 annulated by low rounded undulations which are from one to two 

 lines distant, according to the size of the shell ; intermediate spaces 

 regularly concave. In the larger parts of the shell there are about 

 three annulations to each chamber. The finer surface markings 

 unknown. 



This'species in its young state is rather slender and very gently taper- 

 ing, and, though attaining a pretty large size, is not as robust as most of 

 the associated forms. It bears considerable resemblance to the Niagara 

 shale species which I have refen-ed with doubt to the 0. imlrieatum^ 

 Wahl. ; but the annulations are not so sharply elevated, and the septa 

 are comparatively more distant. The section, in all the specimens 

 examined, is elliptical. It is possible that this may be the species 

 described by Mr. Billings under the name 0. oberon^ the principal differ- 

 ence being in our specimens the prevailing elliptical form of the tube. 



The specimen figured is about nine inches in length, and is represented 

 of the natural size. 



Formation and Locality. — In limestone of the age of the Niagara group, 

 at Waukesha and Pewaukee, Wisconsin. 



Orthoceras loxias, n. s. 



plate XIX, FIG. 7. 



Shell of medium size, elongate, somewhat rapidly enlarging from the 

 apex ; section circular ; siphuncle central or subcentral, scarcely 

 constricted at the junction of the septa ; septa distant about one- 

 fourth the diameter ; chamber of habitation unknown. Surface 

 marked by sharply angular longitudinal carinse with regularly con- 



