3U 



ly double the quantity of potash necessary for the wheat to the tur- 

 nips alone. These facts will appear from the following table : — 

 Salts in an imperial acre of — 



Wheat, . 



The crops of a rota-N Turnips, 

 tion after a single f Barley, 



appUcation of ma- L Hay, 



Total, 1106.7... 172.4... 



nure, viz. : — 



Oats, 



3. On the Fossil Fishes of the Old Red Sandstone of Ork- 



ney. By Dr Traill. 



The author stated, that besides the original localities at Skaill, 

 Ichthyolites have been found at Breckness, Quoyloo, and Kirkwall, 

 in Pomona, in South Ronaldshay, and in Papa-Westray. The spe- 

 cies already recognised from these localities are, 1. Osteolepis ma- 

 crolepidotus. 2. Osteolepis microlepidotiJI. 3. Cheirolepis Traillii. 



4. Cheiracanthus minor. 5. Diplocanthus crassissimus. 6. Dipte- 

 rus macrolepidotus. 7. Platygnattus paucidens. 8. Coccosteus latus. 

 9. Plerichthys Milleri. 10. Diplopterus Agassiz. 



All but the last have been named by M. Agassiz, who determined 

 the generic characters from specimens in the author's possession. 

 The characters of the Diplopterus Agassiz are the following. The 

 genus Diplopterus has two dorsal fins, similar and opposite to two 

 anal fins ; vertebrae continued into the upper lobe of a nearly even 

 tail ; and a wide mouth armed with strong conical teeth. It belongs 

 to the Sauroid family of Ganoid fishes. The species D. Agassiz 

 may be distinguished by a rounded snout ; a large head almost equal 

 to a fourth of its whole length ; a single row of trigonal, hatchet- 

 shaped scales on the ridge of its back, and oblique rows of rhomboidal 

 scales passing from these to the abdomen ; smooth scales, and the 

 dorsal and anal fins rounded at their extremities, and composed of 

 slender rays. 



4. Mr Milne made a verbal commuuication respecting Instru- 

 ments for registering Shocks of Earthquakes. 



The advantages of registering earthquake shocks were first briefly 

 noticed. 1. Such registers would shew whether, as supposed, the 

 shocks were more frequent and violent during certain states of weather, 

 and particular months of the year. If this were ascertained, some 

 light would be thrown on the cause of the shocks, in so far at least 



