35 



necting link between the Orthoceraiite and the Goniatite that has 

 ever been discovered, and consequently no mental conception can 

 be introduced to supply the omission. We describe below twelve 

 species, eleven of which are new, and refer them to the genus 

 Gonintites. They are from different Groups, in the subcarboniferous 

 system and from the Coal Measures. Some have a closed um- 

 bilicus, others an open one, the volutions differ greatly, iu form, 

 and there are great variations, in the septa, some reversing the 

 order of the sinnosites, in crossing the volutions; but we are 

 unable to distinguish characters which we can call generic and by 

 so doing separate them into different genera. We think Prof. 

 Hyatt would not refer all the species to the same genus, and we 

 appreciate his learning, but are unable to follow him in his generic 

 subdivisions. 



GONIATITES BLAIRI, n. Sp. 



Plale 1 V, Fig. 4, side vietc, jxirt of it covered with ihe matrix; 

 Fig. 5, porlion of the ventral or outer margin. 



Shell below medium size, discoid. The sides of the volutions 

 are flattened and inclined toward the ventral or outer margin, 

 which is narrowly rounded or subangular. The umbilicus is open 

 and exposes part of the volutions. Our specimen shows less than 

 one and a half volutions and it would appear that about half of 

 each volution is exposed and that a complete specimen would con- 

 tain about three volutions. Probably the last volution embraces 

 less of the preceding one than the inner volutions do. The sides 

 of the umbilicus are subangular and the greatest lateral diameter 

 of a volution is near the umbilicus, or adjoining the abrupt de- 

 scent to the umbilical cavity. The dorso-ventral diameter of a 

 volution is very little more than the greatest lateral diameter. The 

 volutions enlarge, at first, very gradually, but the enlargement is 

 increased, toward the outer part of the last volution. The surface 

 is marked by furrows, that are directed moderately backward, 

 from the angle at the umbilicus, for about half the diameter of 

 the volution, and then more rapidly curve backward to the pe- 

 riphery which is crossed by a rather sharp angle. The furrows are 

 separated by sharp angular ridges. Septa and body chamber un- 

 known. 



We think there can be no doubt that this species belongs to 

 Goniatites, though none of the septa can be seen. The species is 

 distinguished by its general form, flattened volutions, subangular 

 periphery and transverse curving furrows that form an angle on 

 the ventral margin. 



