68 



Part III. — Twenty-third Annual Report 



For the journey to Fraserburgh the larvae were packed at 3.15 p.m., 

 and were set free at 7.15 p.m., at which time they were all quite lively. 



The vitality of the young lobster under certain conditions is remark- 

 able. Herrick kept them alive in small flat dishes, without change of the 

 water, from one to four days at a time, or until they moulted to the 

 second stage. A case in point occurred at the Laboratory. After one of 

 the journeys to Fraserburgh a few larvae had been left in the dregs of 

 water in one of the carboys. They were discovered 10 days later, and 

 were then alive and active. Two small crabs (Carcinus mcenas) were 

 kept for a week in a little glass cell without change of water, and 

 apparently suffered no ill-effects. 



There was a considerable mortality among the larval lobsters when in 

 the hatchery. As has been so often noted, a proportion of the deaths 

 occurred during moulting. The dead lobsters were sometimes partly 

 eaten. No case was seen of one zoea attacking and killing another, such 

 as Herrick witnessed. A case of cannibalism was noticed in the 

 megalops stage. One megalops was seen eating the tail of another which 

 was still alive. The telson and part of the abdomen had been eaten off 

 when discovered. A cause of considerable mortality is probably starva- 

 tion. It is difficult to supply suitable and sufficient food. 



All the lobster eggs were hatched out by September 10, 1902. 



The Rearing of Lobsters. 



There are two well-marked stages in the life of the lobster fry : these 

 are (1) the first swimming stage, when just hatched (fig. 66, pi. iv.), 

 and (2) the stage when it for the first time takes on the form, and, to a 

 certain extent, also the habits, of the adult (fig. 72, pi. iv.). The former 

 is the first zoea stage, the latter is the megalops stage. Previous to the 

 first zoea stage there is the protozoea, a stage of short duration. The 

 lobster has been described as issuing from the egg as a protozoea. This 

 condition was not observed by the writer. It moults very soon after, 

 and becomes a zoea of the first stage. R. Q. Couch was the first to 

 figure and describe the protozoea. He wrote as follows: — "Several of 

 the ripest bunches of ova were taken off, and by gentle agitation many 

 of the young escaped and swam about very freely, like those of the 

 common crab, and some were artificially extracted to leave no doubt to 

 rest on their parentage. Their bodies are large, stout, and of a deep blue 

 colour, while the other parts are semi-transparent and dotted with red. 

 The eyes are large, sessile, situated on a festoon at the lower and anterior 

 margin of the dorsal shield, and marked at the circumference with radia- 

 ting lines. The interior margin of the shield is w r aved, and irregularly 

 prominent ; the posterior and lateral surfaces are more remarkably so, 

 and are rough, with minute papillary eminences ; and the lower margin is 

 marked with seven minute plaited folds, beneath the five central ones 

 are situated five claws on either side. They are jointed as in the adult, 

 and the anterior pair are shorter and stouter than the others, and ter- 

 minate in a pair of nippers. The tail is longer than the diameter of the 

 body, is extended and composed of five annulations. The termination is 

 forked, but the fork is composed of two flat fan-like expansions separated 

 by a fissure which extends nearly as high up as their articulation." 



Savilte Kent and Fullarton also give drawings and descriptions of this 

 stage. 



The megalops stage is one in which the lobster in its habits resembles 

 more a prawn (Palcemon), as Saville Kent pointed out. The interval 

 which exists between the first zoea and the megalops has been filled in 

 by a varying number of stages. Herrick, for the American lobster, 



