PRODROMITES, A NEW AMMONITE GENUS 257 



regions are now obliterated, either washed away entirely, or 

 covered by the sea, or concealed by later deposits. The first 

 records in the rocks or in text-books do not, by any means, agree 

 with the first appearance of any group in geologic history. This 

 is clearly seen when one notes the constant pushing back of the 

 records of the first appearance of types, that has taken place 

 in the past ten years. Our ideas of the specialization of organic 

 life in Cambrian and even pre-Cambrian time have had to 

 undergo radical changes as the discoveries of new faunas have 

 followed fast upon each other. 



Genus, Prodromites, gen. nov., Smith and Weller. 



Type, P. {Goniatites) gorbyi Miller, 1S91, Advance Sheets 

 Seventeenth An. Rep. Geol. Survey of Indiana, p. go, 

 Plate XV, Fig. 1 ; and Seventeenth An. Rep. Geol. Sur- 

 vey of Indiana, 1892, p. 700, Plate XV, Fig. 1. 



The type species was originally described as a goniatite, but a most lib- 

 eral interpretation of that group could not include this form, which was 

 assigned to that division simply because of its occurrence in Carboniferous 

 rocks. 



The genus Prodromites 1 is characterized by its laterally compressed, dis- 

 cordal, involute, deeply-embracing whorls, narrow umbilicus, high, hollow 

 abdominal keel, and complex, ceratitic septa. Where the keel is broken off, 

 as is usually the case, the abdomen is narrow, slightly flattened, and angular. 

 The surface, so far as known, is smooth, and destitute of ribs, constrictions, 

 or other ornamentation. The septation is the most distinctive feature of this 

 genus, on account of the large number of serrated lobes, and an extensive 

 auxiliary series of lobes and saddles. The ventral lobe is rather long and 

 undivided, the saddles all rounded and entire, the first four or five lateral 

 lobes are serrated, and in addition to these there is a series of several pointed 

 and more or less irregular auxiliary lobes. 



The only Paleozoic form to which Prodromites may be likened is Belo- 

 ceras, which it resembles only in its compressed involute form and the multi- 

 plication of the elements of the septa. The resemblance is not great, but 

 the agreement is fundamental, and these two genera may safely be placed in 

 the same family or phylum. A much greater resemblance and probably kin- 

 ship connects this form with Hedenstroemia Waagen, of the Lower Trias of 

 the oriental region. The best known species of that genus is H. mojsisovicsi 

 Diener, Pal. Indica, Cephalopoda of the Lower Trias, page 63, Plate XX, 



1 The etymology of the word is from the Greek of scout or forerunner. 



