400 Bibliographical 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 our present state of knowledge is pure guess- 
work. Quite a number of ichthyologists are of opinion-—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. 
If Amphiowus be taken as the lowest piscine form (older view), or 
only as the progenitor through the hagfish and lamprey to the 
vertebrate 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. 
Reference is made to Dannevig’s observation that the pelagic eggs 
of certain forms are chiefly shed at night. ‘To this we may add 
that even in the parturition of higher 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 in the pelagic forms do females preponderate, the con- 
trary obtaining in demersal forms? It certainly is remarkable 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 differing. 
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 be 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, &e., so that the eye is there and then impressed on the 
reading of the text. Bnt 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 topie of pelagic fauna is one on which M‘Intosh himself has 
9? 
* Here introduced, but cf. Brit. Assoc. Rep. 1896, reprinted in Nat. 
Science, 1897. 
ee oe) eee 
