1883.] 337 [Hyatt. 



could not have been inherited directly from that genus. The 

 only species known to us is the Triai. (Gon.) costatum, D'Arch. 

 et Vera., Gaol. Trans. Lond., 2 ser. Vol. 6, pi. 31, fig. 1. This 

 has sinuous outlines in the sutures with undivided rounded lobes 

 and saddles, and costated whorls very similar to those of Sandb. 

 tuberculoso-costatum. It can be separated from Fronorites by 

 these same characteristics. 



Pronorites, 1 described by Mojsisovics in Mediter. Trias. Prov. 

 p. 200, includes an exceedingly interesting series of dwarfed forms, 

 which present the marginal divisions of the lobes and saddles sub- 

 sequently characteristic of the Ammonitinae. Genetic connection 

 with the Prolecanitidae seems to be assured by the aspect of the 

 sutures. The form of the whorl, and the later larval sutures have 

 the aspect, number of lobes and saddles, and apparently the same 

 mode of developing the outer first pair of saddles from the first 

 pair of saddles, as in the Prolecanitidae. The lobes are hastate, 

 the saddles linguiform, the ventral is not fully divided by a si- 

 phonal saddle. The divisions are, in their incipient stages, like 

 minute points or saddles on either side of the large funnel lobes. 

 Thus the apex of the ventral is trilobate. The saddles are rounded, 

 but the first lateral lobes are subdivided by two incipient sad- 

 dles in Pron. mixolobus, according to DeKoninck, a fact not veri- 

 fiable in our specimens of this species. There is only one mar- 

 ginal saddle in the first lateral lobe of Pron. cyclolobus. The 

 species, so far as known, are Pron. (Gon.) cyclolobus, sp. Phill. 

 Geol. York. pi. 20, fig. 40-43, mixolobus, ibid, pi. 20, fig. 43-47. 



Popanoceras, 2 nobis, includes species of the Dyas, which are 

 very closely allied to Pronorites, but have more complicated 

 sutures, and approximate more closely to the Ammonitinae. The 

 whorls are more involute and compressed, and are also costated, 



1 Norites, Mojsis., Med. Trias. Prov., p. 201, is described by that author as genet- 

 ically connected with Pronorites. We are forced to differ again from this able author- 

 ity, since the affinities between these forms are due to larval stages of the sutures, 

 which are equally characteristic of Carnites, and some other genera. The form of 

 whorl of Norites and the outlines of the sutures appear to us, as to Griesbach, to be 

 closer to those of S igeceras. Norites is not very remote from Longobardites, which in 

 our opinion is in th Q . young similar to the genus Prolocanites both in form of whorls, 

 and in modes of generating lobes and saddles. It seems to us prossible that t'.ie deri- 

 vation of the group may have been from the lower forms of the Prolecanitidae but not 

 from Pronorites. 



Iloiravov, a round, flat cake. 



PROCEEDINGS &,&.*.&. VOU XXIX. 82 VEB8BXSX, 1884. 



