168 



Report of the State Geologist. 



(</) The entire expression of the species is one of extreme simplicity, 

 corresponding well with its early geologic age. 



Holzapfel has recently described * an Anarcestes (A. Karpinskyi) from 

 the middle Devonian near Wildungen, which resembles closely A. lateseptaftus 

 and A. plebeiformis, though with less numerous and rather deeper whorls, and 

 he has given a figure of the protoconch with the nepionic conch adhering. 

 Unfortunately the degree of enlargement of the figure is not stated and we can 

 not compare its actual size with that in A. plebeiformis. Both protoconch and 

 conch are finely striated, presenting an aspect similar to that of Agoniatites 

 eaopcmms, Van., as represented in the following note. 



The nepionic conch, however, is stated to be free from the protoconch for 

 nearly a half volution.- This mimoceran stage is evidently skipped by the 

 New York species. 



The Protoconch of Agoniatites, Meek. 

 (Aphyllites', Mojsisovics.) 



The species termed by Vanuxem, Goitiatites expansus, was redescribed 

 by Professor Hall as Gon. Vautixemi, the change in the specific name arising 

 from the preoccupation of the earlier term. This species abounds and 

 attains great size in certain localities of the Agoniatites limestone of the Mar- 

 cellus formation ; it is also rarely found in the overlying shales of the Hamilton 

 group. The characters of the adult shell have been fully described and finely 

 illustrated in the Palaeontology of New York, vol. v, pt. 1, and vol. vii, Suppl. 



The species is one of the typical forms of the genus Agoniatites, Meek. 

 Recently Holzapfel has included it among the varieties of Agon, ificonstans, 

 Phillips, thereby expressing the wide geographical 

 distribution of the specific type. The genus 

 includes lenticular, more or less strongly umbilicated 

 shells, characterized by the simplicity of the suture 

 and its slight ontic variations. In early life the 

 suture is purely anarcestian, and at epheby its form 

 has changed mainly by the increase in the promi- 

 nence of ventro-lateral saddles and the lateral lobes. 

 The protoconch, which has not before been de- 

 scribed, is large, its size being great in comparison 

 with goniatites of the later Devonian, but is still «*]^™»\ a ^ 



7 t • t ■ ispartlv broken awav, exposingthe scar 



less than that of Anarcestes pleoeijormis. It is of the si P j»onai caecum. * 25. 

 rather stoutly ellipsoidal, projecting a little at each side beyond the edge of the 

 first whorl. The surface is finely and sharply striated horizontally from the 



♦ Din Kauua mit Maenecoras terebratum Sjuilb , p. 77, pi. 3, fifjs 15-20, 1895. 



