464 ROBRRT GURNEY. 



and habits of the adult. Like the Mco-alopa oE the majority 

 o£ Brachyura it is very aetivCj swimming rapidly by means 

 of its pleopods, the antenna) being carried stretched straight 

 forwards and parallel to one another, the thoracic legs bent 

 np nnder the body. Unlike the zoasa it seems to be in- 

 different to a strong light at night, being neither attracted 

 nor apparently repelled by it. 



It does not seem to be a pelagic form properly speaking, 

 and was only once obtained in the tow-net, and then within a 

 fathom or so of the bottom, in deep water. Some of the 

 specimens moulted in my plunger jars were provided with 

 fine sand, and at once burrowed until covered completely 

 except for the antennae. The act of burrowing is performed 

 just as in the adult by means of the four posterior legs, the 

 chelipeds taking practically no part. If the sand, which 

 must be exceedingly fine, is not deep enougli to completely 

 cover the body, the Megalopa pushes itself backwards till the 

 sand is heaped up above it, often moving backwards in this 

 way for some distance. When covered the antennre are not 

 necessarily held quite parallel, but the position seems to a 

 considerable extent to depend upon the depth to which the 

 animal has burrowed. In the buried position the resj^iratory 

 current is reversed, and sets down the antennal tube, as Mr. 

 Garstang has shown it to be in the adult. The efficiency of 

 the antennal tube as a strainer was well shown by the sand 

 grains resting on the interlocking hairs. One specimen of 

 the Megalopa, and one of the succeeding post-larval stage, 

 were obtained in some sand from Whitsand Bay. 



As to the food of the earlier stages of the larva I have 

 no direct observations to record. Though provided with a 

 constant supply of the smaller plankton organisms, and with 

 other small zoa;as, I have never seen the zoa^a of Corystes 

 taking any food. From the appearance of the contents of 

 the gut it seems likely that the food consists entirely of 

 fioating- algai or diatoms. I have several times seen the 

 zoicas of other forms, such as Eupagurus, devouring other 

 larvce, but it is quite possible that the zoieas of Corystes, at 



