riiODKOMITES. 35 



as is usuallv the case, the abdomen is fiattencd and angnlav. The snrface, 

 as far as known, is smooth, destitnte of ribs, constrictions, or otlier ornamen- 

 tation. The sei)tation is the most distinctive featnro of tliis "ienns, on 

 account of the hn-ge lunnber of serrated lobes, and (extensive auxihary series 

 of lobes and saddles. The ventral lobe is rather long' and undivided, the 

 saddles all rounded ;nid entire ; the hi-st four or livi' lateral lol)es are serrated, 

 and in addition to these there is a series of six or more pointed and more or 

 less irregular auxiliary lobes. 



The only Paleozoic genus to which Prodromitcs may be likened is 

 Beloct'ras Hyatt, which it resembles onlj- in its compressed involute form 

 and in the nuiltiplication of the elements of the septa The resemblance is 

 not great, but the agreement is fundamentnl, and the two genera may safely 

 be placed in the same family or phylum. A much greater resemblance and 

 probable kinship connects this form with Hcdenstnemia Waagen, of the 

 Lower Trias of the Orieiital region. The be.st known species of that genus 

 is H. mojsisovicsi Diener." In Hedenstrmnia, as defined by Waagen,'' the 

 ventral lobe is divided, the external saddle is divided by adventitious lobes; 

 the first four lateral lobes are serrated, and there is a series of about six 

 pointed auxiliary lobes. The form is flattened, iuA'ohite, with narrow and 

 angular abdomen. No keel is known, and the shell is smooth. In 

 Prodromites, on the other hand, the ventral lobe is undivided, and the 

 external saddle is entire and rounded; but in the serration of the first four 

 or five lateral lobes, and in the auxiliary series it is almost identical with 

 Hedenstrmmia, as also in the form, with the exception of the keel, which 

 may not have been preserved in the few specimens known. There can be 

 no doubt that the two genera belong to the same phylum and even family, 

 in spite of the long time that intervened between the Kinderhook formation 

 of the Lower Carboniferous and the Lower Trias. Hedoisfrd'mia (PI. XX^^ 

 fig. 5), according to Waagen," belongs to the family Pinacoceratidic, sub- 

 family Hedenstrocmin;t>, which also contains Glypites Waagen, and Carnites 

 Mojsisovics of the Trias. The family Pinacoceratida3 in the broader sense, 

 as defined by Waagen, contains all forms with compressed involute whorls, 

 an adventitious series of lobes, many lateral lobes and saddles, and an 



«Pal. Indica, Ser. XV, II iniiiliivaii fossilf*, Vol. II, Pt. I, Cephalopoda of the l.owor Trias, p. 63, 

 PI. XX, fig. la-o. 



sPal. Indica, Ser. XIII, Salt Range Fosnilc, Vol II, Fossils from the Ceratite foniiation, y. 1411. 

 'Ibid. 



