10 Part III. — Twenty -eighth Anmial Report 



the ingestion of bacteria, nor from the presence of sewage in the 

 water, so long as the gills are not clogged ; but, on the other hand, 

 such outbreaks of disease are of some significance to Health Authori- 

 ties in whose sanitary areas sewage is being deposited in rivers, 

 estuaries, or on the seashore. 



Abnormal and Diseased Conditions of Fishes. 



Dr. Williamson contributes a paper to this Eeport, in which he 

 describes various abnormalities and diseased conditions which he has 

 observed among fishes, such as tumours in the cod, the lemon dab, the 

 viviparous blenny, and other forms, and also cases of hermaphrodi- 

 tism in the cod, a species in which that condition is not uncommon. 

 He also describes and figures the larvse of the angler (Lophnis), and 

 gives an account of its eggs and those of the halibut, the conger, and 

 the tusk. The ripe egg of the conger has not yet been identified with 

 certainty : the largest yolked eggs observed by Dr. Williamson were 

 0'6 millimetres in diameter, and were found in fishes captured at the 

 end of October and the beginning of November. The same gentleman 

 has also written a paper, illustrated with five plates, describing the 

 larval stages of various species of crabs. The study of these larvae is 

 important with reference to the general question of development and 

 the discrimination of the forms which go to make up the plankton. 

 This paper is not included in the present Report, but is published 

 separately as a Stationery Office publication. 



Parasites of Fishes. 



Several papers dealing with the parasites of fishes have appeared 

 in previous Eeports of the Board, and to the present one Dr. T. Scott 

 contributes a description, illustrated with two plates, of four parasitic 

 trematodes, one of which is now described for the first time. One of 

 them was obtained from the gills of the gar-fish, and the others from 

 the non-edible Ohimcera monsirosa. 



We have the honour to be. 



Your Lordship's most obedient Servants, 



ANGUS SUTHERLAND, Chairman. 



D. CRAWFORD, Beimty-Ghairman. 



D'ARCY W. THOMPSON. 



W. R. DUGUID. 



L. MILLOY. 



D. MEARNS. 



H. WATSON. 



DAVID T. JONES, Secretary. 



