ANIMALS 79 



can be induced into tubes held under water against the 

 surface of the stone. They can then be killed with a 

 few drops of formalin dropped into the sea water in the 

 tube, and at once corked up in the same fluid. Fora- 

 minifera, minute unicellular organisms with complicated 

 shells (Figs, n to 20), can be seen creeping up the glass 

 sides of any tumbler or glass into which some clean sand 

 from below tide-level has been placed. We know little 

 of their life-histories even in temperate seas, and tropical 

 forms are mainly of interest to us for comparison of 

 their shells with those in various elevated rocks. We 

 get their shells, by simply drying the sand — i.e., in the 

 various sand samples we have already collected for 

 more general purposes. Of insects we may mention 

 Halobates (Fig. 139), seen on rock-pools, though a wan- 

 derer over all tropical oceans. Its eggs and larvae are 

 often found on floating cuttle-bones and pumice, fre- 

 quently being confused with young barnacles. Need- 

 less to say any insects in salt water are of value, and 

 should be carefully preserved in 70 per cent, alcohol. 

 There is a spider also (Desis) the distribution of which 

 is interesting. Lastly, we have snakes (Hydrus), 

 dangerous pit-vipers, but yet timid beasts, incapable 

 of harm so long as the body is covered, and the thin 

 parts of the hands are kept well above the surface of 

 the water. 



Of sedentary animals we might make a catalogue of 

 Hydroids, soft corals (Alcyonaria), anemones, corals, 

 sea-squirts (Tunicata), sponges, and Polyzoa, and say 

 that pieces of any and all placed in 70 per cent, alcohol 

 are likely to be of value to specialists, particularly when 

 smaller slips for anatomical purposes are put in 90 per 

 cent, alcohol. We are, however, at the present day 

 beset with difficulties at every turn in respect to the 

 determination of the species of these forms. They have 



