PLATE XXI. 
Fig. 
1. Paleoniscus comtus,' Agassiz. ie Scales magnified. Marl-slate, Thrislington 
Gap. Belonging to the Natural History Society of 
Northumberland, Durham, and Newcastle-on-Tyne. 
Presented by Mr. T. Hodgson. 
2. Paleoniscus longissimus, Agassiz. c, Scale magnified. Marl-slate, Thrislngton 
Gap. Natural History Society of Northumberland, 
Durham, and Newcastle-on-Tyne. Mr. T. Hodgson. 
1 All the figures are of the natural size. 
