"Nov. I, 1877] 



NATURE 



Ascension to utilise the late opposition will be on this 

 account awaited witli much interest. Nevertheless, what- 

 ever degree of opinion might be entertained by competent 

 authorities, it appears to have been felt by those imme- 

 diately responsible for action, in different civilised nations 

 where science is encouraged, that so rare a phenomenon 

 as a transit of Venus could not be allowed to pass with- 

 out every exertion being made to utilise it, and this 

 country may lay claim to an honourable share in the great 

 scientific effort, thanks mainly to the long-continued and 

 admirably-directed endeavours of the Astronomer- Royal 

 to secure this result. 



Several of the stations occupied during the transit of 

 1874 will be available for the transit of 1882, Kerguelen's 

 Land in particular, where at Ingress the sun will be at an 

 elevation of 12°, the factor of parallax being 0-98. In that 

 year there will also be the advantage of observations 

 along the whole Atlantic sea-board of the United States 

 and Canada, where, as pointed out by the Astronomer- 

 Royal in 1868, the lowest factor is 0-95, and the smallest 

 altitude of the sun 12° for observing the retarded Ingress ; 

 and for observing the Egress as accelerated by parallax, 

 the factors are about 0-85, the sun's elevation varying 

 from 4° at Halifax, to 32° at New Orleans, or Jamaica. 

 Australian and New Zealand stations are important for 

 retarded Egress. 



As is well known, the transit of Venus on December 6, 

 1 882, will be partly visible in this country. 



PARKER AND BETTANY'S "MORPHOLOGY 



OF THE SKULL" 

 The Morphology of the Skull. By W. K, Parker, F.R.S., 



and G. T. Bettany, M.A. (London : Macmillan and 



Co., 1877.) 



IN the minds of most of those who have paid no special 

 attention to the subject the skull is regarded as a 

 bony case formed to contain the brain, together with the 

 face. There is also a constancy in the number and posi- 

 tion of these bones which lead to the apparently necessary 

 conclusion that occipital, sphenoid, parietal, and other 

 elements are fundamental cranial structures ; so that an 

 exhaustive study of their relationships and variations 

 might be thought entirely to cover the subject of skull 

 structure. 



That such is not the case has dawned upon us since 

 the elaborate researches of Rathke and other able em- 

 bryologists, among the foremost of whom must be placed 

 Profs. Huxley and Gegenbauer, who have been followed by 

 Mr. Parker, the author of the work under consideration, 

 who on account of his peculiar aptitude for manipulation, 

 his untiring zeal and his immense experience, has placed 

 the subject of cranial morphology upon a footing infinitely 

 more satisfactory than it has previously been. His 

 numerous memoirs in the Transactions of the Royal, 

 Zoological, and Linnean Societies form a mine of biological 

 facts, so beautifully supplemented by their accompanying 

 illustrations. The perusal of them all, in their proper 

 sequence, is however a task>nly to be undertaken by the 

 specialist, and it is on this account that we have no small 

 degree of pleasure in being able to give a notice of *' The 

 Morphology of the Skull," a work of less than four 

 hundred pages, in which is collected, condensed, and 



digested the mass of information spread through the 

 larger memoirs. 



The work consists of a series of chapters on the skulls 

 of carefully-selected types of the five classes of the 

 Vertebrata. Those chosen are :— 



1. The Dog-fish and Skate. 



2. The Salmon. 



3. The Axolotl. 



4. The Frog. 



5. The Common Snake. 



6. The Fowl. 



7. The Pig. 



These are each described in allj stages from their 

 earliest appearance in the blastoderm to their adult con- 

 dition. Following each chapter is a brief resuine of the 

 peculiarities which have been observed in other members 

 of each group, in such a manner that the student of any 

 particular form can learn almost all he may require with 

 reference to any special member of the sub-kingdom. 



The primitive trabeculas cranii, together with the para- 

 chordal cartilages and the branchial arches are traced from 

 their earliest development until ossification in and around 

 them has reached the limits of the different types. The 

 insufficiency of our data for the determination of the 

 cranial segments is prominently brought forward, although 

 the moniliform constrictions of the anterior extremity of 

 the notochord in the fowl and in the urodeles is stated, and 

 thought to suggest a segmentation. On the subject of 

 the vertebral theory of the bony skull, Mr. Parker tells us 

 that " only one bony segment, the occipital, can be said to 

 be clearly manifest in the skulls of fishes and amphibians. 

 And in these forms there are no good grounds for 

 assigning to the cranial bones special names indicating a 

 correspondence to particular parts of vertebras. From 

 the study of adult structures in the mammalian groups 

 skull-theories have been devised, lacking the basis of 

 embryology ; and gi anting that they express some of the 

 truth respecting the highest forms of skull, there is only 

 injury to knowledge in arbitrarily interpreting the lower 

 forms by them. In reptiles the skull becomes much more 

 perfect, but with wide variations in the different groups, 

 such that they cannot be merely subordinated to and 

 explained by the mammalian type. A careful study of 

 the growth of the bird's skull, again, will show that it is 

 impossible to express its composition on a simple formula 

 derived from vertebral structures. But from the lower to 

 the higher forms of vertebrates we can discern a growing 

 away from the primordial type of skull towards and into a 

 loftier development." This result of the extensive investi- 

 gation upon which it is based is somewhat paradoxical. 

 The " loftier development " of the highest types results in 

 a skull some of whose components may be compared in 

 detail with some expression of truth to vertebra, whilst in 

 the lower forms a similar comparison cannot be said to 

 hold. And yet true vertebrae themselves, fully developed 

 as far as their essential details are concerned, are found 

 in forms far from high in the scale. 



Mr. Parker's invaluable investigations besides their 

 importance in a comparative anatomical point of view, 

 have done much to demonstrate the degree of stress 

 which must be laid on facts of cranial structure in 

 problems relating to classification. His labours have led 

 him to elaborate the instructive classification of birds 



