Pakeozoic Fossils. 387 



Axis arched, wide at the fore part with a steep downward 

 slope, but at about the middle at the 7th rib contracted, and the 

 slope less steep ; axis separated from the sides by a smooth area. 

 Ribs clearly cut, with a few spines ; obliterated near the smooth 

 margin. 



Sides rounded in front, vertical behind, with a false margin 

 commencing about the fourth rib from the front. Ribs continu- 

 ous with those of the axis in front, but behind they slope stronglj- 

 backwards and meet the smooth inner margin in a sigmoid curve. 

 The first rib bears two large spines, supported on a common swol- 

 len base, and the third also bears a m.edium sized spine. 



There are portions of four bod 3' rings on the specimen, show- 

 ing the fulcra very clearly ; each of the ribs bears a large spine 

 external to the fulcrum. 



Width about 7 cm. ; length about 7.5 cm. ; depth at the 

 front, 4.8 cm. ; at the 7tli rib, 3.5 cm. ; at the iOth rib, 3.2 cm. 



Remarks. — If the present specimen were flattened bj- one 

 side being folded under, and the axis brought into about the same 

 plane as the other side, the specimen would be very similar to 

 that figured but not named by Lake on Plate XXVII. , fig. 2. The 

 smooth area between the axis and the sides is the same, as is the 

 strong forward bending of the side ribs towards the end of the 

 pygidium. Lake's specimen, however, is far more spinose than 

 the Albany Museum type. I feel sure that Lake's specimen, which 

 I collected myself, has been fiattenel; it occurs in a micaceous 

 shale in which pressure is easily transmitted to the organic 

 remains included in it, and while I agree with Lake that the form 

 is clearly distinguishable from H. herscheli, 1 cannot endorse his 

 view that the affinity of the species is with the Silurian types of 

 Homalonotus which are characterised by their flat bodies. 



It is to this species that Prof. Haug's H. herscheli, from the 

 Algerian Sahara, comes nearest. I am doubtful, however, of the 

 correctness of tlie view that the Saharan lower Devonian forms 

 are of a South African or American facies. S'jnri/er roasseaui. 

 Verneuil, and Goleoprion gnicile, Sandberger, are Coblenzian ; 

 Stroplieodonta oriskama, Clarke, I admit has an American aspect, 

 for it comes very close to our SL concinud, Moriis and Sharpe ; 



