144 CONTRIBUTIONS TO CANADIAN PAL/EONTOLOGY. 



and the tubercles on the abdomeB had two points so closely set as to 

 look like parts of one big tubercle, or as if they had oi-iginated from 

 soroe such division of a large tubercle." 



Arniotites, Hyatt. (Gen. nov.) 

 (=«=Balatonites arietiformes. Mojsisovics.) 



Shell discoidal, whorls moderately numerous, strongly compressed 

 at the sides, everywhere in close contact, but very slightly embracing, 

 so that the umbilicus is wide and open and almost the whole of the 

 inner volutions is exposed to view periphery simply cai-inated, "keel 

 single, smooth, with slight linear channels on either side, or none, 

 according to the species :" surface of the outer whorls simpl}' costate. 

 "The pilas (ribs) arise fi-om folds and are smooth, perfectly developed, 

 straight on the sides, bending forward at the geniculse, which are 

 sometimes noticeably prominent. The sutural line has not been seen, 

 but, judging by analogj^, the lobes were probably dentate and the 

 saddles smooth." 



In reference to this genus Prof. Hyatt wi-ites as follows : " The care- 

 ful examination of the specimens collected by Dr. Dawson convinced 

 me of what I had long suspected, that the genus Balatonites of Mqjsiso- 

 vics contains three distinct genera. This eminent authority had, in 

 fact, himself clearly seen and distinguished three groups, but did not 

 consider them to be of generic rank. The shells of Balatonites arieti- 

 formes, Mqjsis. (Ceph. der Mediterr. Triaspi-.) have complete pila.'. with- 

 out tubcrcules, and entire keels in the youug, and the latter are only 

 very slightly, if at all, ridged in adults. I propose for this group the 

 name of Arniotites, in allusion to the close resemblance of the shells to 

 the Arni.oceras of the Lias, a fact first noticed by Mojsisovics. 



The type of Mojsisovic's genus is Balatonites Balitonicus (V. 1, kurse 

 Uebers d. Amm. — Gattun. d. Mediteri'. u. juvav. Trias; Verb. d. k. k. 

 Eoichsan., 1870, No. 7, p. 139). This belongs to the second group, the 

 Balatonites gemmati. These shells have heavily tuborculated pila3, a 

 line of tubercles I'cplaces the keel and they resemble Trachyceras in 

 general aspect. The sutures are similar to those of Arniotites, the 

 lobes being dentated and the saddles smooth. 



Mojsisovics' third group, the Balatonites acuti, is the most distinct 

 of the three. The shells have sutures with smooth lobes and saddles, 

 true keels are not present, but the abdomens are exceedingly acute in 

 some species. In the few species known, the whorls are much com- 

 pressed and the mode of growth discoidal — the whole presenting a 



