Prof. T. R. Jones — Destruction of Marine Animals. 539 



frost on Molluscs between tidal lines and at low water in severe 

 winters. 



2, It is stated that Oysters are killed by cold (at freezing-point) in 

 less than three or four feet of water" (^Chambers's Journal, No. 837, 

 Jan. 10th, 18S0, p. 29, etc.). 



3. In the lower half of an ice-sheet, 8 feet thick, in Barrow 

 Strait, Dr. P. C. Sutherland observed that " scores of small Fishes 

 (Merlangus polaris) had been caught and cruelly detained, and 

 starved to death," while " myriads of Infusoria and siliceous AlgfB 

 luxuriated in the utmost profusion " [Sutherland's Journal of Capt. 

 Penmfs Voyage, etc., 2 vols. 1852, vol. i. p. 224, and pp. 275-6). 



IX. Diseases and parasites appear to be common evils among Fish. 

 The Salmon, Gold Fish, etc., are known to suffer from parasitic 

 Algaj. 



1. "Fish Disease. — The fish in the Seine at Paris appear to be 

 suffering from some malady. Large numbers are cast on the banks 

 dead, almost in a state of decomposition, and cannot fail to render 

 the water unwholesome for drinking purposes. Immense shoals also 

 float on the surface of the river with their heads out of the water, 

 and are easily taken by men who wade in the stream with nets and 

 baskets. Such fish are, however, quite unfit for food" (Neivspaper). 



2. In a Newspaper dated August, 1867, it is stated that " The 

 banks of the Lake of Constance are at the present moment covered 

 with vast numbers of dead fish, the result of a malady prevailing 

 among them. A similar epidemic recently prevailed in the waters 

 of the Lake of Geneva." 



3. A great mortality among the Fishes in the Gulf of Mexico is 

 noticed in the Annals and 3Iag. Nat. Hist. ser. 5, a'oI. viii. p. 238, 

 1881, from an American Journal. For two years near Florida, along 

 a belt of water at a small distance from the shore, but over a space 

 of 200 miles, the water was brick-red in colour, and its surface 

 covered with dead fish ; so also was the beach ; and in fishing 

 smacks, with live fish in "wells," passing through this water all the 

 fish were lost by death. After careful examination, the result 

 arrived at was that the fish probably died from " more or less para- 

 sitic Algae." 



X. Miscellaneous causes of general death of Fishes and Molluscs. 



1. As in small aquariums, so in ponds, when the proper equilibrium 

 of living and dead organisms is disturbed, and the vegetation fails to 

 use up the escaping carbonic acid, the animals of all sorts die and 

 add to the black mud and noxious gases of decomposition. Such a 

 result occurred in a piece of water at Claremont, in Surrey, the late 

 Professor Teunant informed me. 



2. " The occasional outbreak of a ferruginous spring from coal- 

 workings will kill the river-fish for miles" (Geol. Mag. Vol. IX. 

 p. 339, August, 1872). 



3. We know that sewerage, limewater, and purposed poisons kill 

 river-fish to a great extent. In hot countries poisonous trees aud 

 herbage fallen into water have been said to kill fish. 



4. Li";htnino; as a destructive aerent. " That fish are stunned in 



