BRACHYURI. 187 



died ill the close of November, without exuviation, Plate XLIV. fig. 8, 

 back ; fig. 9, breast, shewing the roe. 



The shell is sometimes cast very suddenly ; wherein all naturalists 

 seem to be taken by surprise. 



A small specimen, obtained on April 8, whose limbs did not expand 

 an inch and a half, cast its shell unexpectedly, there being no indications 

 of exuviation half an hour before the event. When observed, the new 

 shell was scarcely free of the old. 



At the same date, the quantity of spawn on another specimen was 

 immense ; the ova reddish, with an orange tinge, overspread half 

 the under surface, extending to the very margin of the shell above the 

 animal's feet, and investing all their roots. — Plate XLIII. fig. 3, upper 

 surface ; fig. 4, under surface. 



The chief breeding season of the Portunus pusillus comprehends 

 April and May. 3.1any specimens are then laden with the vivid ver- 

 milion roe, fig. 6, which fades on advancing nearer to maturity, fig. 5. 

 At that time detached capsules are also found in their vessels, fig. 7. 

 Some breed much later in the year, as in October and November, when 

 they are also full of roe. The young, figs. 8, 9, 10, were \evy active on 

 escaping from the capsule. 



The specimen, Plate XLIII. figs. 1, 2, which had been freed of the 

 spawn on July loth, and afterwards cast its shell on August Gth, was in- 

 vested by a white zoophyte in the subsequent month of February ; the 

 colour of the shell, whence this later product rose, had faded, yet the ani- 

 mal fed readily, though the zoophyte, which proved a Vorticella, with 

 numerous branches and ])ells, remained. It died in March, without any 

 other obvious cause, when a cluster of at least an hundred capsules was 

 exhausted before exuviation. 



In as far as I have been able to discover, this important change never 

 takes place under other conditions. But, I repeat, the proximity of 

 the two incidents is unknown. As the whole integuments separate 

 without reserve, it is plain that other exuviation, preceding an exhausted 

 ovarium, would expose the brood to destruction, whereas experience 

 shews safety attends its postponement. 



