10 



Part III. — T treaty-third. Annual Report 



At 13 and 14 inches they were mostly four years of age, 

 while some in which the lines of growth indicated five years 

 measured 11 J, 14 J, and 18 J inches, and one measuring 20 inches 

 was shown to be four years old. 



The paper is illustrated by three plates showing the otoliths, 

 scales, and bones. 



The Life-History of the Lobster. 



In the present report will be found a paper, illustrated by four 

 plates, in which Dr. H. G. Williamson gives the results of his 

 observations on the life-history of the lobster. An account is 

 furnished of the experiments on lobster-culture which were made 

 at the hatchery, the " berried " or egg-bearing females being kept 

 in a suitable tank, the larva? as they hatched being carried away in 

 the overflow to receptacles where they were retained. Hatching 

 was found to take place during the night, and the first young 

 lobsters were observed on 11th July. 



The larval and early young stages which were reared at the 

 Laboratory are described and figured in detail. Certain dimorphic 

 forms of the zoea were discovered among the larva?, and they 

 attracted attention, since, so far as known, such forms have 

 not hitherto been recorded and described. Attention was directed 

 to the behaviour of the lobsters during the time they were kept in 

 confinement at the Laboratory, that is to say, three years in certain 

 cases. Among them only one was known to have spawned its 

 eggs. Casting occurred frequently, more frequently apparently 

 than normally occurs with lobsters in the sea, and the increase in 

 size immediately after moulting was found to be very small ; 

 reproduction, moreover, seemed to be inhibited. 



Various observations made on the condition of the ovary, the 

 periods of spawning and hatching, the number of eggs carried by 

 the female, the growth of the lobster, and on other points connected 

 with its life-history and habits, are incorporated in the paper. 



Dr. Williamson also furnishes a further note on the life-history 

 of the edible crab, treating specially of the hatching of the young. 



The Parasites of Fishe*. 



Dr. Thomas Scott, who is still prosecuting his researches on the 

 parasites of fishes, contributes a paper on these organisms to the 

 present report, in which several species not previously recorded 

 from the Scottish seas are described, the descriptions being 

 illustrated by a number of figures. This paper contains descriptions 

 of seventeen species, twelve of which belong to the Crustacea and 

 five to the Trematoda. 



One of the crustacean species described is found living in the 

 nasal fossa? of several kinds of fishes, as the cod, haddock, whiting, 

 &c. Another was obtained in the mouth of a three-bearded rock- 

 ling, and others on a sturgeon, a porbeagle shark, and other fishes. 



The Trematoda, which are leach-like in form, were obtained on 

 the gills of the grey gurnard, the ballan wrasse, and the bass 

 {Lohrax lupus). 



