PLATE IV. 



Orthoceras Porteri, a. H. Foord. 



Fig. 1 a. Fragment with the greater part of tlie body-chamber. 1 b. Transverse 

 section of the same. 1 c. Body-chamber of another individual. 1 d. Longitudinal 

 section of another specimen. Little Island. Dublin Museum of Science and Art. 

 (Page 9.) 



Orthoceras subclavatum, A. H. Foord. 



Fig. 2 rt. A nearly complete specimen, showing the wavy and oblique septa. 

 2 h. Transverse section. 2 c. Longitudinal section of another individual, showing 

 the beaded siphuncle. Little Island. Dublin Museum of Science and Art. 

 (Page 13.) 



Orthoceras venabull'm, .4. H. Foord. 



Figs. 3 a, 3 6. Specimen with the surface slightly polished to show the septa. 

 The extremity has been separated from the rest of the specimen in order to 

 represent the latter of the natural size. 3 c. Longitudinal section from the same 

 individual. 3 d. Transverse section, showing the siphuncle. Clane. Dublin 

 Museum of Science and Art. (Page 10.) 



