596 p. W. GAMBLE AND F. W. KEEBLE. 



living or the dead animal exposed to these conditions take 

 place with sufficient slowness to admit of careful examina- 

 tion. 



When trawling and shore collectings at night or early 

 morning, the colours of the animals as they appear when 

 taken out of the net are observed by the light of paraffin 

 lamps. Though, by this means, it is impossible to judge 

 the fine shades of colour with sufficient accuracy for close 

 comparison with those noted under the more constant con- 

 ditions described above, yet it serves to give a general idea 

 of the colour of the animal; nevertheless with practice a 

 fair judgment can be made. The susceptibility of Hippo- 

 lyte varians to temperature changes, incidentally referred 

 to, is only one indication among many of the fact that it is 

 less hardy than many of its allies. 



We found it necessary to spend a considerable time in 

 devising an apparatus in which specimens under experiment 

 could be supplied with aerated water and with food. Aided 

 by a grant from the British Association Committee, we 

 constructed an apparatus which serves for the culture of 

 the animals, and also for determining whether they flourish 

 better in vessels through which a constant stream of water 

 is passing or in similar vessels through which a current of 

 air is drawn. Inasmuch as the water current in the former 

 induces the air current in the latter series, we have a means 

 of accurately determining this question. After a prolonged 

 trial we find that the prawns on the whole flourish better 

 in what we will call, for convenience, the "air -circula- 

 tor" dishes. It is true that we made no effort to exhaus- 

 tively demonstrate this interesting point, being only in search 

 of the most favourable conditions for experimenting upon 

 Hippolyte. 



Our apparatus consists of a large aspirator bottle, of a 

 capacity of about one and a half gallons (Fig. 1, a). The 

 neck of the bottle is fitted with a cork bearing three tubes 

 (a, h, c). The lateral opening below has a cork bearing one 

 tube, the exit-tube. One of the three former tubes is of 



