38 FAUNA OF THE CORNBRASH. 



dorsal, superior lateral, inferior lateral, etc., apply ; but the shell varied much in 

 form, and could be arranged in groups and families. 



From this point of view the classification given by Zittel in his ' Handbuch,' 

 in 1884, embodies the principle of a natural classification much more than the 

 new classification by Hyatt, which has been substituted for it, but which goes 

 back to the partial principle of classifying all by one organ. In the phraseology 

 above set out the Cornbrash Ammonites are all of them angustisellate pro- 

 siphonates and belong to the groups Mgocerati&a} with the family Stephano- 

 ceratida?, 2 and Arietida with the family Harpoceratidae. 



Family Stephanoceeatid^e. 



Ammonites with numerous transverse ribs, which cross the periphery Avith- 

 out change, but which tend to unite on either side at some point towards the 

 umbilicus. 



Genus MACROCEPHALITES, Zittel. 



This genus was established by Zittel in his ' Handbuch der Palasontologie,' 

 I Abth., II Band, in 1884, witli the following definition : Involute, with broad, 

 rounded exterior, all the whorls regularly covered with numerous sharp ribs, 

 which divide into two or more near the narrow, deep umbilicus. Sutures much 

 divided. 



The name was founded on part of the group of Macrocephali instituted by 

 von Buch (' Abh. Berlin. Akad.' (1830), 1832) for the allies of the shell known as 

 Ammonites macroc&phalus. These allies are indicated by Zittel as A. morrisi, 

 Opp., 3 A. macrocephalus, Schloth., .1. tumidus, Rein., and A. herveyi, Sow., etc. 

 It is fortunate that the name proposed, being a generic one, will cover the speci- 

 mens figured by Zittel (fig. 655), as well as that to which the name of A. macro- 

 cephalus was given by Schlotheim, for they are different species. The latter was 



1 See Art. " Cuttle Fish," Enc. Brit., ed. x. 



2 It has been suggested that the name Stephanoceras might be confounded with that of the rotifer 

 Stephanoceros, but, as a matter of fact, it never has been so confounded by those who know them both 

 — nor has any one taken Rhinoceros to be ti Cephalopod. The termination ceras has been taken to 

 mean " horndike as a whole," and ceros to mean "horned" in some part. Thus, Stephanoceras, & 

 horndike animal with a crown ; Stephanoceros, an animal with its horns in a crown ; Rhinoceros, an 

 animal with horns on its nose. 



3 This name is given by Oppel to the species figured by Morris and Lycett from the Great Oolite 

 as A. macrocephalus. It is certainly distinct from that species; it is also distinct from A. viator, 

 d'Orb., to which Lycett (' Supplement,' p. 121) later referred it. This is a Plnjlloceras from the 

 Mediterranean province ! 



