644 



MOLLUSCA 



PHTLUSI VI 



the dorsal (antisiphonal) lobe is undivided, in the most primitive forms, and bifid in the 



more specialised groups. 



The entire family 

 is supposed to have 

 been derived from 

 Lecanites, and through 

 that genus to have been 

 connected with Nomis- 

 moceras of the Carboni- 

 ferous, and Gephyroceras 

 of the Devonian. 



Fig. 1225. 



Cladiscites torruxtus (Bronn). Upper Trias ; Steinbergkogel, near Hallstadt, Austria. 

 A, B, Lateral and anterior views. C, Suture-line. 



Subfamily A. Lecanitinae Hyatt. 



Primitive discoidal shells like those of the Prolecanitidae, with short rounded entire 

 saddles and lobes like those of Prolecanites, but ventral lobes divided by short com- 

 paratively broad and entire siphonal saddles. There are all 

 stages in the development of these saddles, so that their 

 aspect is rather variable. There are as a ride but two 

 principal lateral saddles and lobes, with one auxiliary .saddle 

 and shallow lolie on either side in primitive species, but in 

 others the number of auxiliaries may be considerably in- 

 creased. Antisiphonal lobe entire, and often 

 long and acute. The zygous dorsal lobes are 

 very slight so far as known, and entire ; 

 merely marginals in the dorsal saddles. 



Paralecanifes Diener (Fig. 1226). Per- 

 mian and Triassic. Lecanites Mojs. ; Kyma- 

 FiG. 1226. Fjo. 1227. tites, ParaTcymatites Waagen ; Proavites 



Parahcaniles arnoMl H. BiuliotiUi^ eryx Avthsihei' ; Badiotites Moisisovici^ (¥ IS. 1221). 



and S. Lower Trias ; Idaho (MUnst.). Keuper ; rp ■ \ o / 



(after Hyatt and Smith). St. Cassian, Tyrol. J- nas. 



Subfamily B. Meekoceratinae Waagen. 



Shells smooth, compressed, discoidal and involute, and as a rule with narrow and 

 more or less flattened venter. Sutures in many forms have a tendency to extend the 

 inner lateral saddles or lobes, and to develojj a corresponding series of auxiliaries ; 

 and this is carried to an excessive extent among some highly involute shells. The 

 ventral lobes, however, are apt to remain broad and shallow ; their arms become 

 highly denticulated excejit in the Lecanitinae where they are narrow and rounded. 

 Saddles entire and generally somewhat elongate and linguiform, but plainly of the 

 Lecanites type. Antisiphonal lobe, so far as known, long, nari-ow and bifid. Ex- 



