M>. OB m HI.nlllKIMl AN BE \Ni II. 



and in Volume II he figures Week. ■ PI ites XIV . XVI., and Pa 



XV., XXI. The figure of extracottahtm bIiows an old whorl which is acute, 



I>ut nt 1 1 involute. Among diacoidal shells, Wah Plates X\ , XVI., 



malum, Plate X\ 1 . and hapbpfychum, Plato XVII., bIiow thai the whorls ol 



their earlier nealogic and adull stages arc without channels. Wah, anuophyUum, 



Plate XIX. Fig. I a, Bhows a verj old Btage with subacute trigonal whorl, and 



pilsB repla 1 by folds. Wah. megasioma, Plate XVIII. Fig. 2, "-. showe 



tier ii with pilaa continuous across the abdomen in the adull and 



senile PI tea X\ 111 . XX.. - wpiychum, Plate XX , 



\\ and dipbpiychum, Plate XXL, also belong to this ge- 

 nus. The last two are senile specimens, with subacute outer whorls, and all 

 the al discoidal shells exhibiting transitions from Psilocema to Schlo- 



theim 



There are, however, involute forms in this series also figured l>\ Wahner in the 

 work, but in Volume IV. These are Wah. Gtadoni, Plate XXVI. Fig 

 Emmriehi, Plate XXVI. 1 We 

 doubt whether either <>f these involute forms can 

 garded as transitional t<> Scblotheimia, 

 by Wahner. 

 I - i!i- of our work upon the nealogic 



- and their meaning in s ata, and all 



other iow that series arose only from dis- 



coidal shells, and probably never originated from 

 the compressed and involute forms. These arc 

 themselves invariably discoidal and less com;' 

 in their own young, showing them in every case 



to hi-. derived from sheila having depressed abdomens and dii 



la 



from in front, 

 ibdomen, of the youni 

 I . tfli r Wihner, ibon ing 1 1 >•• 



iOTolation ol Ih - 



lomi ii i>f 



in tllCM 



Unteren Lias von Spezia," describes and figures dwarfs or 



/ / mrichi under the name of Guidoni. Wahner thinks 



I i. | .'. are referable to his Quidom, and 



i be identical with hit / Th< last - to ua a verj remarkable 



form iteral and abdominal constrictiona 



SCHLOTHEIMIA 



The form varies in this I to involute, but the umbilici arc 



overed in. The whorls arc usually flattened nunc or less on the 



i lom. n depre i. In the n< ••- this form is common. 



> w 



pKorn- 



