﻿154 CERTAIN GENERA AND SPECIES OF LYTOCERATIDJ5. [Feb. I905, 



EXPLANATION OF PLATES XV & XVI. 



[All the figures are of the natural size.] 

 Plate XV. 



Northampton Sands, Aalenian [Hemera scissi]. 



Figs. 1&2. Pachylytoceras phylloceratoides, sp. nov. Spratton Ironstone Work- 

 ings, Brixworth, near Northampton. Collection of Mr. Beeby 

 Thompson, F.Gr.S. Eig. 1. Side-view. 2. Section of whorl at A 

 (restored) outline. 



Figs. 3 & 4. Pachylytoceras aalenianmn, sp. nov. Spratton Ironstone Workings, 

 Brixworth, near Northampton. Collection of Northampton 

 Museum. Fig. 3. Side-view : inner whorl showing tonclosum- 

 stage. Fig. 4. End-view. 



Plate XVI. 



Northampton Sands, Aalenian [Hemera scissi]. 



Figs. 1 & 2. Alocolytoceras tceniatum (Pompeckj). Same locality and collection 



as P. aalenianum. Fig. 1. Side-view. 2. End-view. 

 Fig. 3. Pachylytoceras phylloceratoides. Peripheral view, in outline (restored). 



[For the excellent photographs from which these Plates have been reproduced, 

 my cordial thanks are due to my friend Mr. J. W. Tutcher, who happily com- 

 bines great photographic skill with extensive geological knowledge.] 



