166 



Report of the State Geologist. 



limestone matrix while the inner whorls have usually become involved in the 

 clayey portions and are destroyed. Some etchings of the rock have, how- 

 ever, offered solid barite replacements of the inner whorls, and upon these the 

 following observations are based. 



Professor Hall called attention to the resemblance of this rare American 

 shell to the Gon. plebeius, Barrande from the Bohemian etage Gi, an horizon 

 corresponding with that of the former species ; its close alliance with Anureestes 

 lateseptatus, Beyr. is very clear. In the mature shell there may be not less 

 than twelve volutions with no tendency on the part of the whorls to become 

 involute. The whorls themselves are exceedingly broad and very shallow, 

 even at the eighth volution the whorl being four times as wide as deep. At 

 the same time the length of the air-chambers is constantly great, having at the 

 eighth volution one-half the width of the whorl, and maintaining very much 

 this relation from the primitive whorls onward. 



The Protoconcli. The protoconch, though not obtained quite free of 

 envelopment, we find to be of immense size, as witness the figures here given. 

 It is transversely elongate or obtusely fusiform, in direct contact with the 



Fignreo 3, 4. Anareestet plebeiformii. Side views of nepionic shells showing surface striations extending over the proto- 

 conch. x25. 



first volution and carries very distinct transverse ornamental lines almost to 

 its distal surface. 



Buanco has recorded a very large protoconch in the anarcestian species G. 

 subnautilimis, var. vittiger* but its size is less than one-half that of this 

 species. 



* Palaeontographica, xxvii, pi. vii, flg. I. a, b. c, 1881. 



