PLATE I.' 



Orthooeras Leinsterense, a. II. Foord. 



Fig. 1 a. Specimen showing the body-chamber and much of the septate part 

 of the shelh 1 b. Longitudinal section of the same, showing the septa and the 

 position of the siphuncle. 1 c. Convex surface of one of the septa showing the 

 siphuncle. These figures are somewhat more than one half of the natural size. 

 Clane. Dublin Museum of Science and Art. (Page 1.) 



OliTHOCERAS VARIABILK, A. R. FoOvd. 



Fig. 2 a. Specimen with body-chamber and nearly all of the septate pai't; the 

 latter has been polished to show the septa. 2 h. Longitudinal section showing the 

 septa and a fragment of the siphuncle. 2 c. Transverse section with siphuncle. 

 2 d. The same, near the apex. These figures are somewhat more than one half of 

 the natural size. Clane. Dublin Museum of Science and Art. (Page 2.) 



Okthocebas Sancti-Doulaghi, ^4. H Foord. 



Fig. 3 a. Fragment of the septate part of a large specimen. 3 b. Longitu- 

 dinal section, showing the septa and the position of the siphuncle. 3 c. 

 Transverse section with siphuncle. 3 d. Fragment of a smaller specimen, showing 

 the body-chamber. 3 e. Transverse section of the same, showing the siphuncle. 

 St. Doulagh's. Dublin Museum of Science and Art. (Page 5.) 



' All the figures in this and the following plates are of the natural size, except where 

 otherwise stated. 



