484 Transactions. 



days, and then were liberated in the harbour on the first of the 

 ebb tide. A technical account of these embryos is appended 

 to this note by Mr. Gr. M. Thomson. 



All the adults had finished spawning by the 10th December, 

 but they will be retained, if possible, in one of the tidal ponds, 

 in order to ascertain if moulting will take place, and whether 

 spawning is annual or biennial. As showing the fecundity of 

 the crayfish, 394,100 eggs were gathered from a specimen 

 measuring only 9 in. The egg is 0'8 mm. in diameter, and is 

 attached to the swimmerets by means of fine filaments during 

 the period of incubation, which probably extends for about nine 

 months of the year. Considerable numbers are still retained in 

 a large glass tank, and it is hoped that a few may be reared 

 through the various brephalops and megalops stages. 



Note on the Development of Palinurus edwardsii, hy George M. 

 Thomson, F.L.S. 



The embryo, on emerging from the egg, has the characteristic 

 Phyllosoma appearance (Plate XX, -fig. a). The length of the 

 body, from the middle of the front margin to the extremity of 

 the pleon, is 2 mm. The carapace is fully 1 mm. in length, and 

 is nearly circular in form, with large well-developed eyes on stout 

 pedicels. At the centre of the front margin, between the bases 

 of the eye-stalks, there is a well-defined ocellus. The antennae 

 are 1 -jointed, and are nearly as long as the carapace. The anten- 

 nules are considerably longer, and bear a number of. plumose 

 setae, by the lashing and waving of which the minute animal 

 progresses through the water. At this stage the other limbs 

 are more or less curled around and folded under the body, and 

 appear to be functionless, there being no trace of the plumose 

 filaments on the pereiopoda, by which later they swim. 



How long this first stage lasts was not clearly made out. 

 Probably it is only a few hours, for no moult was detected by 

 Mr. Anderton, yet after a time the plumose filaments of the 

 antennules had quite disappeared, while those of the three 

 posterior pereiopoda were seen to be developed. In this second 

 stage (Plate XX, fig. h) the length of the body from between 

 the eyes to the end of the pleon is 2-5 mm., and the spread of 

 the limbs is rather more than 6 mm. The carapace tapers more 

 to the front than in the preceding stage, and the eye-stalks are 

 relatively longer and more prominent. The divisions of the 

 pereion were not clearly made out behind the broad base of the 

 carapace, but it bears 5 pairs of pereiopoda. The antennae are 

 1 -branched and apparently 1 -jointed ; they are shghtly longer 

 than the eye-peduncles, and bear a single setae on their outer 

 margin and two or three at their extremity. The antennules 



