ZOOLOGY AND BOTANY, MICROSCOPY, ETC. 
525 
on this some discussion of the general theory of limbs. His results as 
to the relation of the appendicular musculature to the appendicular 
skeleton, and as to the extent of displacement which the girdles may 
show in relation to the vertebral column, furnish indirect but effective 
evidence in favour of Gegenbaur’s theory of the visceral arch origin, as 
opposed to the Thacher-Mivart-Balfour-Dohrn theory of the origin of 
paired fins from lateral folds. 
Cranial Nerves and Sense-Organs of Fishes.* — Mr. F. J. Cole 
points out that it is “ unphilosophical,” at present at any rate, to regard 
the cranial nerves as a fixed number of serially arranged pairs ; that 
even in the case of the branchial nerves, where the serial arrangement 
is most marked, it would be hazardous to assert that each represented 
a metameric unit; that the cranial nerves form an association whose 
form is due practically to physiological necessities, and not to a survival 
of an original serial arrangement ; and that the lateral sense-organs on 
the head are certainly not metameric, and only secondarily so in the 
body. 
Biology of the Salmon.f — Dr. D. Noel Paton edits an interesting 
‘ Report of Investigations on the Life History of the Salmon,’ three 
papers from which we have summarised separately. The report deals 
mainly with the condition and capability of the food-canal while the 
salmon are in fresh water, and with the changes in the weight and com- 
position of the muscles, reproductive organs, &c. 
That the return from the sea to the native river is not governed by 
the growth of the reproductive organs and n>sus generaiivus , is shown by 
the fact that salmon are ascending the rivers throughout the whole year 
in all stages of reproductive development. The salmon returns when it 
has accumulated the necessary supply of food-material. The conclusion 
of Miescher-Ruesch is confirmed that the salmon, at least before spawn- 
ing, does not feed during its sojourn in fresh water. The solids greatly 
diminish, but the percentage of water in the flesh increases. A detailed 
study of some of the changes as regards fats, proteids, pigments, &c., 
has been made by the various authors who share in this report. 
Markings of Boidae.J — Dr. J. Zenneck has made a very thorough- 
going study of the markings in this large family. After describing a 
long series of particular cases, he leads up to the most general conclusion. 
“ All the species discussed may be arranged in a relatively small number 
of series. Each link of such a series differs in the same way from its 
preceding or succeeding link in the same series. Thus the various 
links of a series may be regarded as various steps in one and the same 
process.” In short, Zenneck confirms Eimer’s observations and conclu- 
sions as to the wall-lizard, but over a wider field. The facts seem to 
the author to point very clearly to definite progressive variation along a 
few lines. Apart from its evolutionary interest, the memoir is of 
importance in regard to classification and bionomics. 
* Trans. Liverpool Biol. Soc., xii. (1898) pp. 228-47. 
t Report of Investigations on the Life History of Salmon. Fishery Board for 
Scotland, 1898, 176 pp. 
X Zeitschr. f. wiss. Zool., lxiv. (1898) pp. 1-384 (8 pis. and 28 figs.). 
