14 



Part III — PAghteenth Annual Report 



functionally immature ; all those above 5f inches were found to be 

 mature and fertilised. The male crab becomes ripe at a smaller 

 size, and all those above 4-J- inches are probably mature. The males 

 and females are in almost equal abundance, the examination of 

 several thousands of specimens showing that 98 males exist to 

 every 100 females. 



The crab spawns its eggs, which may number several millions, 

 from November to January, in deep water, and they are hatched 

 inshore in July and August, the period of incubation being seven or 

 eight months, batches of eggs, as a rule, being carried in two 

 successive years, at least, before the crab casts its shell. With 

 regard to casting — an important subject from the point of view of 

 close-times which have been proposed — it was found that while it 

 may occur during a large part of the year — namely, from May to 

 November inclusive — it takes place principally in July, August, and 

 September. The largest numbers of soft crabs are obtained from 

 August to November inclusive, and principally in September. 

 Experiments showed that the time taken for a soft crab to harden, 

 and therefore to become legally marketable, varied considerably. 

 The great majority take from three and a half to four months, 

 and large numbers remain " soft " in the legal sense from 90 

 to 100 days after casting. When the crab is approaching the 

 mature size casting probably occurs once a year, but mature 

 crabs above 4-J- inches do not cast every year, and the female 

 not oftener than once in two years. With regard to dis- 

 tribution, it appears that the post-larval and earliest young 

 stages, up to f of an inch in breadth, are probably restricted to the 

 shallow shore waters ; those from this size up to 2\ inches are to be 

 found between tide-marks ; a little larger (up to 4 inches) they are 

 littoral, outside low-water mark ; and those of 4 inches and up- 

 wards, or the mature group, are found in winter offshore, beyond the 

 twenty-fathom line at Dunbar, and in the spring and summer in the 

 inshore waters. 



Numerous experiments were made, with interesting results, 

 regarding the seasonal migrations, and the movement of those which 

 were marked and recovered are indicated on a chart accompanying 

 the paper. The migration seawards appears to occur during August 

 and September, and the inshore migration begins usually in 

 February. The statistics of the crab fishery and its regulation are 

 also considered. In connection with this investigation it was dis- 

 covered that the Board had not the power, which is possessed by 

 the District Fishery Committees in England, to permit the 

 possession of berried crabs for scientific research, or for any purpose 

 except for use as bait, in terms of the Act of 1877. A number of 

 berried crabs had been obtained in ignorance of this difficulty, but 

 the provision referred to greatly restricted the investigation, and it 

 would be advantageous if the Board obtained the same powers as 

 the English Committees have to allow the use of such crabs for 

 scientific investigations. 



The Paeasites of Fishes. 



In a paper by Mr. Thomas Scott the results of his investigation 



