STRUCTUBE OF CEKTAIN PALAEOZOIC DIPNOI. 
165 
his 'Fauna der Gaskohle ' (vol. ii. 1889), published numerous excellent 
figures of detached bones of Sagenodus, but a large proportion o£ them were 
unidentified, and his letterpress added little to what was already known. 
More recent contributions will be mentioned incidentally and in the List of 
Literature. 
The available material has been re-examined by us, and the results are 
here stated, largely in the form of figures. 
Fig. 2. 
Sagenodus. Cranial roof of six individuals, to illustrate the extent of variation. A-D, 
Atthey Coll.,* from the Low Main Seam, Newsbam ; E, V, Royal Scottish Museum, 
from the Virtuewell Seam, Newarthill. 
In its general structure the skull of Sagenodus resembles that of Ceratodus 
m having an extensive cartilaginous neural cranium, of which no traces are 
ever to be seen, surrounded and supported by well-developed membrane 
bones. The bones which covered the top of the head frequently remain 
connected together in the fossils, but no complete articulated skulls are 
known. 
* Except where otherwise stated, the originals of all figures ai-e in the Atthey Collection. 
