TH1KD, OB VERMICEB \N BRAN< II. 1 55 



The young whorls for a very 1 i m 1 1 1 1- . l stag tooth, then the rounded 



..'ii and immature pita of I I i- introduced after 



ni'l we have for ;i bI iration, according to 1 1 1 « - 



semblance to Bomi 



The adults are i baracteriied by qnadragonal forma and flattened, keeled, and 



channelled abdomena The pita are Btraight, with distinct genicuta bending 



In one variety of Verm. < i the genicuta arc tuberculated, in 



other examples they are smooth. 



..iv!' arietian proportions in the adults, though they retain the 

 immal rtions of the young until a late period of growth, and often even 



in the adult stage. The abdominal lobe is longer than the superior laterals, and 

 the superior lateral saddles shallower than the inferior lateral-; the auxiliary 

 saddles and lobes maj dly hive a backward trend in the young, but this 



is not fo unl in adt 



The old - n- the keel, and has Btnooth, somewhat flattened and con- 



I'hi- is very distinct from the similar Bta I loceras, in which 



the ki ind the whorl becomes rounded. The extreme form assumed in 



ontrasted with the adult whorl, can be best described as trigonal 



•II similar to the aenile Btages of Caloceras before the keel is lost, 



and t ; gibbous than in the trigonal senile whorls of the more 



highly developed -|" I The sutures degenerate, the abdominal 



lorter Our observations on the geratologous period in this 



tory as in aome others, senile specimens being of rarer 



dt. in his " Aram. Schwab. Jura," Plate VII., figures under 



then: veral fragments of large shells, 



whieh of Benile metamorpl >s belonging to this genus, 



but we tie to designate the probable Although the last whorls 



rfectly smooth in these figures and tl convergent, 



and th ibly narrowed, the keel and channels are still persistent 



The whorl in the oldest specimen had become bo excessively altered by 



in tint it was smooth and helmet-shaped, as in Psiloceras, and the 

 chain • though a low broad keel '•till remained. 



B tish Museum a fossil, HMo nun. in diameter, labelled, 

 /' Nfewbold Quarries, Rugby, Warwick- 



I i whorls compressed and smooth, as in P 



til channels preserved on part of the last volution. We 

 identifii '• ' nybtari, but eminent paleontoli 



land have expressed their opinion that it might be a specimen i 

 ch indebted to Mi Henry Woodward, of the British M 



I, but unfortunately this i- not sufficient to settle the 

 nvolved. We have had no opportunity for re examination, and should 

 ■ •red our former opinion as probably erroneous b 

 ••> Wright, /' ilatus 



• n in the i ! 

 whorl." ' cmbling this, and also n -till m advanced 



