102 



MOLLUSCA, 



No. 212. Ammonites latus, Park. 



From the Gault (Cretaceous), Folkestone, England. 



No. 213. Ammonites macrocephalus, Schloth. 



This is the type of Von Buch's group " Macrocephali," 

 which resemble the "Corojiatl," but are ordinarily more 

 inflated, and have tubercles nearer the umbilicus. 

 From the Middle Oolite, Wurtemberi?. 



No. 214. Ammonites mammilatus, Schloth. 

 From the Lower Cretaceous of Macheromenil, France. 



No. 215. Ammonites Mantelli, Sow. 



.\C<t^lYr-ii> 



The Cretaceous Ammonites appear 

 to have had such tendency to variation, 

 that specilic names have been needlesslj' 

 multiplied, and hence this well known 

 Ammonite has been described under 

 several synonyms. It belongs to the 

 group " RJwtomagenses." From the 

 Lower Chalk, St. Florentin, France. 



No. 210. Ammonites margaritatus, Mumfort. 



Sjmonym of A. amaltlieus, Schloth, and type of 

 group "^TO«/i!7ia," of Von Buch, or Ammonites 

 with cordate keels. This is an exceedinglj' vari- 

 able species. From the Middle Lias, Charmouth, 

 England. 



No. 217. [521, Cast]. Ammonites obtusus, Sow. 



This Ammonite is well known from the Lower Lias of England, where the 

 casts of the interior, preserved in beautifully colored calc spar, are known as 

 "Tortoise-shell Ammonites." It belongs to the group "Arietes." This speci- 

 men is from the Lower Lias, Charmouth, England. Diameter, 9. 



