CORALLINE LIMESTONE. 



337 



703. 4. ONCOCERAS EXPANSUM (n. sp.). 



Pl. LXXVII a. Fig. 2 a, b. 



Shell ventricose, rapidly expanding in the middle ; septa closely arranged, very slightly 

 convex; siphuncle subdorsal ; surface? 



This fragment, from the rapid expansion towards the aperture, is sufficiently characteristic to 

 indicate a distinct species. The fragment consists of about five septa preserved in their natural 

 form, though destitute of the shell. 



Fig. 2 a. Lateral view of the specimen. 



Fig. 2 b. Transverse section, showing the position of siphuncle. 



Position and locality. In the Coralline limestone at Schoharie. 



{Collection of John Gebhard junior.) 



In addition to the specimens described above, Mr. Gebhard has recently discovered a spe- 

 cimen of Trochoceras much more depressed than T. gebhardii, and which may prove distinct 

 from that one, though it is impossible to decide from the single imperfect specimen in question. 

 He has also discovered an Orthoceras, which may prove characteristic of the mass ; though 

 from the fragment in my possession, I am unable to describe it with sufficient accuracy to be 

 made available. 



The Coralline limestone exists in place at several localities on the east side of the Helderberg, 

 but I have had no opportuity of examining these places in detail. It is not improbable that 

 many more species may be added to those already known. 



CRUSTACEA OF THE CORALLINE LIMESTONE. 



The Crustacea known in this rock, consist of a single species of trilobite, and a single 

 species of Cytherina. 



704. 8. CALYMENE CAMERATA. 



Pl. LXXVIII. Fig. I a -/. 

 Calymenc camerata. Conrad, Jour. Acad. Nat. Sci. Philadelphia, Vol. viii, p. 278, 1842. 



Cephalic shield wide, subcrescent-form ; anterior margin elevated in a strong fold, a deep 

 groove separating it from the front of the glabella and cheeks ; glabella broader and nearly 

 straight in front, furnished on each side with three distinct tubercles, the posterior one very 

 large and prominent, the anterior one minute ; eyes opposite to the central lobe of glabella ; 

 the iurrow between the glabella and cheeks very deep ; a projecting lobe from behind the eye 

 touches or unites with the middle of the three lobes of the glabella, and a similar projecting 



