400 Bihliographical Notices. 



demersal, type, are but safeguards against the enormous disad- 

 vantages of the buoyant habit. Not that there is a superiority in 

 pelagic spawning, as one would infer from the authors' remarks. 



Masterman reasons * that pelagic spawning is the more primitive 

 form. To such argument there can be no positive answer, inasmuch 

 as all depends whether marine or freshwater forms were first 

 evolved — and this in onr present state of knowledge is pure guess- 

 work. Quite a number of ichthyologists are of opijiion — and solid 

 proofs are not wanting — that many freshwater forms readily adapt 

 themselves to a salt-water habitat, and equally so the opposite. Nay 

 more, examples are numerous and marked where, in the same fish, 

 seasonal or part of every-day life, so to say, is spent in both waters. 

 \i Amphioxus be taken as the lowest piscine form (older view), or 

 only as the progenitor through the hagfish and lamprey to the 

 vertcbiate true fish (later view), then, from what we know of their 

 spawning-habits and littoral sojourning, there may be as great a 

 chance that ground-spawning is the primitive mode. 



Kefcrence is made to Dannevig's observation that the pelagic eggs 

 of certain forms are chiefly shed at night. To tliis we may add 

 that even in the parturition of higlier vertebrates the same holds 

 good. It is averred that the number of floating eggs bears a ratio 

 to the breeding fishes, with which axiom most would agree. As 

 to their ruthless destruction and the intense after-struggle for 

 existence, it would be hard to deny. To this is necessarily related, 

 wherefore iji the pelagic forms do females preponderate, the con- 

 trary obtaining in demersal forms ? It certainly is renuirkable that, 

 say, the sprat and herring, so closely allied, should one be pelagic, 

 the other demersal in habit ; so that the adult structure evidently 

 has no influence as a determining factor. Nor does oil-globule in 

 the egg or size of the latter characterize a particular group of 

 fishes, the closest allies again dift'ering. 



In the short chapter "Fish from a Pelagic Egg" it is shown 

 that in most cases prior to and immediately after hatching the kind 

 of fish can he recognized by its pigmentation. Some are of canary 

 tint, others ruby-red, or stone-coloured, or black and yellow, or 

 alone black-banded, these hues being only youthful stages in colora- 

 tion. Some, again, have great post-larval fins or spines and such- 

 like ornamentation, which are modified or lost as age advances. 

 Woodcuts dispersed in the text represent several of these changes 

 as cod, ling, &c., so that the eye is there and then impressed on the 

 reading of the text. Eut this part of the subject is so replete with 

 interest and suggestion, that this chapter could well have been 

 expanded with figures accordingly. The authors deftly call atten- 

 tion to similar stages in the development of the higher vertebrates 

 as indicating genetic relations with ancestral forms. 



The topic of pelagic fauna is one on which M'Intosh himself has 



* Here introduced, but cf. Brit. Assoc. Rep. 1896, reprinted iu Nat. 

 Science, 1897- 



