3848 The Zoologist — February, 1874. 



apply the rule to the conveyance of aquarium animals. To give 

 an actual example, I find that the following animals, and some 

 others, may, at certain temperatures, be safely sent from Southend, 

 in Essex, to the Crystal Palace in boxes (or preferably in baskets) 

 packed in damp freshly-gathered sea-weeds : — 



1. Nearly all the Sea-Anemones. 



2. Most of the Echinodermata. 



3. A large number of Annelids. 



4. Many Crustacea. 



5. Some of the Tunicata. 



6. Nearly all shelled Mollusca, both univalves and bivalves, and 

 some of the Nudibranchiata. 



7. The following fishes : — Amphioxus (this once came alive from 

 Naples in a post-letter, and four of them so brought arc still alive 

 in the Crystal Palace Aquarium), plaice, soles, brill, roclilings, 

 eels, gobies, blennies (of three species), sea-scorpions. 



The explanation of the reason why they so travel is this : they are 

 surrounded with moisture in a sufficient degree to keep their bodies, 

 in the case of sea anemones, and especially in the case of the spe- 

 cialized breathing apparatus in the other animals, to enable respira- 

 tion to be carried on. Take, for example, any fish so conveyed. It 

 is not immersed in water, but its gills are kept wet by such very thin 

 films of water that their thinness, otherwise shallowness, enables 

 them to be instantly oxygenated by contact with the atmospheric air, 

 which enters the apertures of the containing box or basket, and which 

 permeates the entire mass, and therefore the gill-filaments are kept 

 wet and separate from one another, and the blood uninterruptedly 

 flows through them and is aerated as it does so, oxygen being 

 absorbed from the perfectly aerated water, which thus does double 

 duty, in a measure. I admit that the balance thus maintained is a 

 delicate one, and is easily disturbed by external causes. Thus a 

 heated atmosphere would cause the moisture to evaporate and the 

 gills to dry up, and the circulation of the blood would be arrested, 

 and the fish or other creature would soon die. So also great cold 

 would freeze the gills iuto a temporarily dry mass, and death would 

 likewise ensue. It will be observed that many of the creatures 

 1 have enumerated never voluntarily leave the water, either in the 

 sea or in aquaria, while others do go out of the water of their own 

 accord, in tanks and in the ocean. But there is one thing which 

 I do not yet understand, and which I should be very grateful to 



