PLATE V. 



Okthoceras l^vigatum, F. M'Goy. 



Fig. 1 a. Cast of an individual of which a portion has been lost. 1 b. A 

 septum of the same, showing the siphuncle. 1 c. Fragment of another speci- 

 men. 1 d. Fragment with part of the test, showing transverse strias. 1 e. A 

 portion of the test of the same specimen enlarged. Ardlaman. Dublin Museum 

 of Science and Art (Geological Survey of Ireland Collection). (Page 14.) 



Orthoceras Wrightii, S. Haughton. 



Fig. 2 a. The type specimen, showing the ornamentation. 2 b. Body-chamber 

 of the same, showing at the base the obliquity of the septa. 2 c. Ornamentation 

 of the surface, much enlarged. 2 d. Septum showing the siphuncle. Clonmel. 

 In the Collection of Mr. Joseph Wright, F.Gr.S., of Belfast. 2 e. The specimen 

 from Clane, drawn for comparison with 2 a. Dublin Museum of Science and Art. 

 (Page 16.) 



Orthoceras pilum, A.. H. Foord. 



Fig. 3 a. Specimen showing the septate part only, imperfect at both ends. 

 3 b. The last septum preserved, showing the siphuncle. Little Island. Dublin 

 Museum of Science and Art. (Page 13.) 



Orthoceras Hindei, A. H. Foord. 



Fig. 4 a. Fragment consisting of nearly the whole of the body-chamber, with 

 a few septa attached. 4 b. Longitudinal section of the same, showing the 

 siphuncle. 4 c. Transverse section of the same. Little Island. Dublin Museum 

 of Science and Art. (Page 12.) 



