FOURTH, OB < OBONICEB \N BB \N< II 17', 



Kll;>l Si BS1 1:11 S 



Coroniceras kridion, Htati 



IMntr 111 l u -,,,.,,„ II. Ml I | C . 0. 



i. II v ' i i: . ( \ ■ ; AI|M*n, pi. in fig I •', 



S 



The pita were already visible <»n the first pari <>f the third whorl, but when 

 they began could not be ascertained. <>n the firel quarter of the third whorl 

 the flattened abdomen of the younger volutions became more elevated, and the 



\.i- introduced. The keel continued to increase in prominence then 

 bul the channels, which are faintly visible on the fourth whorl, only broaden out, 

 ami iio no1 Bensiblj increase in depth, alter they reach the lost pari of thi 

 volution. 



form acquired on the third or fourth whorl is carried throughout life, the 



• hI\ from the dorsum to the abdomen ; the abdomen i- elevated. 



tin* pita are either overhanging or Blightly tuberculated on 1 1 1 « • latter pari ol 



the third whorl, bul very soon the curvature becomes equal and the tubercula- 



lisappear, though the genicuta sometimes remain verj prominenl even on 



There are three specimens of this Bpecies in the Museum of Stuttgardt, 



the exact position of which, with relation to Buckhndi, is considered uncertain 



I young in all t In ■-<• specimens are smooth, and precisely 



similar to the young of the -| imens from the Angulatus bed, from which the 



adults, however, differ slightly. The tubercular processes on the casts, as in all 

 other specimens ol th are blunt, and covered Bmoothly l>\ the Bhell, no) 



protruding into Bpines. The specimens in the Bucklandi bed have longer, 

 r whorls with different Butures, bul these differences are nol sufficient to 

 In-ill : they are probably closely allied direct descendan 

 ()|i|»-l claimed to 1 1 . i \ • • had the original of Zieten's description, and, according 

 to him, it - ' . which i- found with ami under B 



I is the only Bpecies answering to this description and agreeing with 



Zieten's figure in having tuberculated pita, slightly divergent Bides, i 



abdomen, and prominenl keel. There are :hannels in Zieten's figure, b 



i in the full-gt n thej are vei \ -hallow 



I i lull- and tbn mens from MUhringen, labelled Bodltyx (No 



i tli M ol Si "_ irdt, from the Angulatus eone Thi 



appear to be identical with .1 ( D'Orb., bul the apparent tubercles 



were merely covered Btnoothl) by the shell, and nol continued out into po 

 ns there is a fossil from Fildei No ■ 178 i, which is pn • 

 ind con fit in- i!. 

 lose approximation in the ch the youn 



inal l"i in- 



