2:")<l LITKs. 



Turrilit<* Sr,n'<int<'riaim.<. Orb., is also to In- referred their, 

 which is distinguished by its habits from nil other Turrilites. 

 and approaching very closely the earlier whorls of //r/rrorr/v/.<. 

 with which also, according to Pictet, it has in common the un. 

 symmetrical build of the lateral lol.es. Possibly T. Senequieri- 

 finnf< is only the young of what in the adult slate is a lli'terocerax 

 provided with an irregular shaft or bodv. as Pictet has already 

 considered it. 



Fifty-one species. 



Genu< BACUL1TES, Lamarck. 



The completelv straight Ammonites of the cretaceous have 

 been embraced in the genus Baculites and form a very good 

 natural group, which in the structure of the first lateral loin 1 is 

 allied to Lijloccrux and //(unite* : in fact, between a Ham iff* 

 with two straight limbs and a Baculites there is no important 

 difference. A list of species of IhtriiliU'.x and a repetition of 

 the diagnosis of the uvnus would be superfluous, a* no change 

 is here made. 



(ienus PHYLLOCERAS, Suess. 



Shell discoidal. involute, with feeble sculpture, sometimes with 

 coiisi rictions or varices. lines of rnr\vth direetel t'orw.Mrds ; 

 ItodN'-chamber shoi'1 . mai'^in of aperture siniph- with somewhat 

 produced lobes on the external side; no aptychus; lobes 

 numerous, diminishino- regularly in size, laterals without sub- 

 division into principal paired branches; leaves or lobes of the 

 Middles very much rounded: antisiphonal lobe two-pointed. 



The Ph\ llocerat ida- bi'anch off, according to von Mojsisovics. 

 trom stems of the monophyllic lA'toccratid;e of t he Trias : the 

 Li('ol(n-i,.;iHy oldest forms :ire still distinguished by few lobes 

 and a somewhat wider umbilicus. Within the limits of certain 

 series of forms a very <-oii-tanl di reet ion of variation becomes 

 apparent in such a way that a steadily progressive complication 

 and increase in the number of saddle lobes or leaves takes place. 



The M-enus fully retains the type in the cretaceous which it 

 assumed in the Jurassic, so that a doubt as to their position can 

 never arise; namely, a reduction and simplification ofthelobular 

 line never takes place, which would seem to indicate an atlinity 

 here to the cretaceous C'-rfitifrx. as has been thought by some 



