200 



The rate of growth, phosphorescence, and geographical distribu- 

 tion of the group are then noticed, and the best method of collect- 

 ing the different forms is pointed out. In searching for the minuter 

 forms, the naturalist is recommended to select a likely pool, and to 

 lie down on the rocks beside it, peering into it patiently and 

 intensely, and never forgetting to look for the shadows, " for in 

 following them he will often secure the reality." The overhanging 

 seaweed must also be lifted up, for under it grow many of the 

 minute species. 



Dichotomous tables, which greatly facilitate the identification 

 of species, follow ; and lastly the scheme of classification adopted is 

 fully explained. 



The class Hydrozoa is divided into three orders — Hydroida^ 

 Syphonupliora, and Discophora. The order Hydrvida being further 

 divided into the sub-orders Athecata, Thecapliora, and Gymno- 

 cliroa. The first and second of these have a polypary — the third, 

 containing the single genus Hydra, is entirely without. The 

 Athecata {Corynidce of Huxley and Tubularina of Johnston) 

 have no true calycles or capsules ; while the alimentary and repro- 

 ductive zooids of the Thecaphora (Sertularidce of Huxley) are in- 

 variably protected by true calycles and capsules. The Gymnochroa 

 {Hydridce) again, are free, while the others are always ultimately 

 fixed. Now, the natural alliance of the order stands thus : — 

 Gymnochroa, Athecata, Thecaphora. "Why, we should like to know, 

 does the author destroy this natural sequence by placing the 

 Gymnochroa last ? The sub -orders are further divided into twenty- 

 two families, and these again into fifty-eight genera, containing 

 about one hundred and sixty species. 



We have only noticed the introduction, and of the body of the 

 work, can only say that it is admirably arranged, and shows that the 

 author is equally well acquainted with the literature of his subject, 

 as with the living forms which he so graphically describes. 



A list of works on the Hydroida, and an index to the text and 

 illustrative woodcuts, complete the work. 



In conclusion, we can recommend this work as a most delightful 

 companion to the sea-side ; and we may safely say, as the author says 

 of Johnston's " Zoophytes," that " it will always rank, with the 

 ' Corallines ' of Ellis, amongst the classics of natural history 

 literature." 



J. H. 



