138 SOME NEW SPECIES OF AMMONITES. 



ites, and this will probaLly become more evident as new forms 

 are found, and complete mouth-borders to other species discovered. 

 Another important point too, is the length of the body chamber, 

 but there is not the .slightest need to make sections of specimens 

 to find this out, thereby spoiling fine examples. In nearly every 

 species some one or two specimens have sufficient test removed 

 to show the last suture line, and if not, it can easily be removed 

 with a little weak acid, thus saving the trouble and expense of 

 cutting sections. 



The ammonites, as far as the Inferior Oolite is concerned, are 

 divided somewhat in the following manner : — 



Ammonites. 



I. Arcestidae II. Lytoceratidae III. Aegoceratidae 



I. Arcestidae contains Amaltheus in the Inf. Oolite, and also 



Arcestes, Lolites, &c. 



II. Lytoceratjdae contains Lytoccras in the Inf. Oolite, also 



Mamites, Phylloceras, &c. 

 m. Aegoceratidae is divided into (1) Aegoceratites, (2) Har- 

 poceratites, and (3) Stephanoceratites. 



(1) Aegoceratites contains Aegoecras and Arietites, 



both in the Lias. 



(2) Harpoceratites contains Harpoceras, Oppelia, 



and Haploceras. 



(3) Stephanoceratites contains ^teiohanoceras, 



Sphaeroceras, Cosmoceras, 

 Pe7'isphinctes, Ancyloceras, 

 and Toxoceras. 



Amaltheus ? Stephani, Nobis, plate i., fig. 1 a-b. 



Shell sub-discoidal, somewhat compressed, very involute, 

 umbilicus being small ; ornamentation merely very fine lines, 



