PAUBOSTOLOOT OF NEW YORK. 



GONIATITES COMPLANATUS, var. PEKI.ATU3. 



l'LAI.l I iXX, I 10. II 



Goniatite.1 complanatus, var. ptrlatus. Hail. Inscriptions of New Bprciea of Con'mtMir. p. 1. 1874. 



<• '< Twenty-seventh Rep. N.Y. State Cab. Nat. Hist., p Y.Vi. 1875. 



•• - " Illustrations of Devonian Fossils: Cephalopoda, pi. 70. ISTti. 



Siikll large, discoid ; the proportions of lateral and transverse diameters not 

 determined; the shell being flattened by compression, the original rotundity 

 U not known. 



Volutions gradually expanding from the apex ; about four or five in num- 

 ber, all of which are exposed in the wide umbilicus. The inner volutions 

 are embraced by the successive whorls to nearly one-half their width. The 

 transverse section was apparently somewhat trapezoidal or semi-elliptical, 

 with the base deeply indented by the preceding volution, and the postero- 

 lateral angles auriculate. The enlargement of the inner volutions of the 

 tube is very gradual. In its flattened condition the width of the exposed 

 portion at the end of the second volution is less than five mm.; at the end of 

 the third volution it is nearly nine mm., while the embraced portion has a 

 width of twelve mm. The entire width on the chamber of habitation at half 

 a volution from its origin is about thirty-two mm. 



Chamber of habitation large, its capacity being considerably greater than 

 all the septate portion of the shell ; its full dimensions unknown. Aperture 

 not determined, but apparently it has been trapezoidal, with the apex but 

 slightly convex and deeply sinuate ; the sides little expanded laterally, but 

 with concave or broadly sinuate margins, and the base indented by the pre- 

 ceding volution. The baso-lateral angles have been auriculate. Air-cham- 

 bers regular, as far as observed, having a depth of four mm. at their origin, 

 where the diameter of the tube is ahout eighteen or twenty mm. 



Septa thin, regular, curving backward from the umbilical margin, and 

 describing a shallow lobe, which occupies about one-quarter of the width of 

 the volution, and thence recurving, include a moderately deep, somewhat 

 regularly convex Baddle, from the summit of which they curve toward the 

 periphery ; but their character on the outer part of the volution has not 



