12 Part III. — Twenty-fifth Annual Report 



and condition of the reproductive organs in the common mussel in 

 various months of the year are described, specimens having been 

 kept in aquaria. At the Bay of Nigg the common mussel was 

 observed to spawn in April and in June, but its spawning time is 

 known to be more extended. Observations were also made on the 

 growth of the mussel and the conditions favourable and unfavour- 

 able to growth, as well as on its movements and the anatomy of the 

 byssus and foot. 



The Invertebrate Fauna. 



Dr. Scott, in continuation of his work among the smaller marine 

 Crustacea which have been obtained in the course of the fishery 

 investigations, has prepared a paper, printed in this Eeport, on a 

 number of interesting forms. Two of the species which are dealt 

 with were discovered as parasites on the piked dogfish, and are 

 here described for the first time, and another occurs as a commensal 

 in the branchial chamber of large ascidians. The paper is illustrated 

 with three plates. 



We have the honour to be, 

 Sir, 



Your most obedient Servants, 



ANGUS SUTHERLAND, Chairman. 



D. CRAWFORD, Deputy -Chairman. 



D'ARCY W. THOMPSON. 



W. R. DUGUID. 



L. MILLOY. 



D. MEARNS. 



H. WATSON 



WM. C. ROBERTSON, Secretary. 



