182 " CRUSTACEANS. 



cluster, but in two clays longer the parent died, as if unable to relieve it- 

 self from such an oppressive load. Some mucor, besides, was afterwards 

 discovered on part of the roe. 



The density of the mass refines gradually ^vith time as it relaxes in 

 clusters, and the ca]5sular integument is extenuated, so as to expose the 

 included young. Next it bursts, to allow the escape of its mature contents. 

 The multitude of young discharged from a prolific parent is very 

 great, the spawn still adhering to the shell as in preceding examples. 

 Also the contents totally void of all resemblance to the features of their 

 kind, are very minute, not exceeding half a line in length, the anterior 

 part large, the rest slender. Some have a dorsal spine, Uke the thorn of 

 a briar, which, however, is for the most part wanting, but all have two 

 red eyes, and the body is speckled under the microscope. — Figs. 7, 8. 



The young animals are extremely delicate, and very short-lived ; it 

 seems impossible, notwithstanding every precaution, to preserve them 

 durino- any metamorphosis that may lead to their ultimate form. One 

 fact worthy of notice, common indeed to all this section of the Cancer 

 tribe, is exemplified here : while an excessive profusion of roe impedes 

 the action of the female, instmct induces her to rise higher and higher 

 on the limbs, as if on tiptoe, to keep it always safe from pressure ; this 

 is obviously the more essential, as the roe is never deposited. 



But on some occasions the parent seems desirous of relieving itself 

 of certain portions of the spawn, whether to lessen the inconvenience of 

 such a burden, or from its approaching decay, and this it can easily do 

 by means of its pincers. 



A vast quantity of loose minute white globules covered the bottom 

 of a vessel containing females on the 8th of March. None proved to be 

 prolific. Nor has it done so when occurring in the same manner on other 

 occasions, though carefully treated. Even where the mass of roe is pro- 

 lific, numerous single capsules are detached by the parent, and I appre- 

 hend that entire clusters are also separated. 



At all times clusters of roe may be severed with scissors, for obser- 

 vation, without the parent suffering any injury. The whole attains 

 maturity particularly in May. The two groups of young represented, 



