SCIENTIFIC SUMMARY. 
447 
an investigation like that which has "been briefly described, and many minute 
details might have been added to this account ; but it appeared to me to be 
desirable to limit the details, as far as possible, to those which were sufficient 
to establish the remarkable physiological fact that the mole, at the time 
of birth, is endowed with organs of vision of considerable perfection, while 
in mature age it is deprived of the means of sight in consequence of certain 
changes which take place in the base of the skull, terminating in the de- 
struction of the most important structures on which the enjoyment of the 
sense of sight depends. 
The Measurement of Teeth. — In a paper laid before the Royal Society in 
May last, Mr. Busk gave some very important advice relative to the 
method of giving the measurement of teeth. He says that the respective 
measurements, which may be taken with a pair of sharp-pointed caliper- 
compasses, having been pricked out upon the equidistant horizontal lines, 
the points showing the length and breadth of each tooth are connected by 
straight lines, and a sort of figure is thus obtained which, in nearly all 
cases, will be characteristic of the genus or family, and in many instances 
sufficient to determine the species also. In some cases, as for instance in 
Canis and Viverra , the odontograms are at first sight so nearly alike that 
recourse must be had to the pattern of the teeth in addition, as before 
alluded to. In order to render figures of this kind easily comparable inter se, 
it is necessary that they should be drawn upon some common scale for the 
distance between the horizontal lines. This is, of course, entirely arbitrary, 
all that is requisite being that it should not be too great nor too small. 
The Growth of Shells . — The Proceedings of the Royal Society (June 16) 
contain a very interesting paper by Professor L. Macalister on this 
subject. He says that while engaged in arranging the large collection of 
shells in the Museum of the University of Dublin, he was led to mak 
measurements of univalve shells in order to see whether any deduction o 
zoological importance might be drawn from these valuable geometrical 
observations, and more especially to determine whether it might be possible 
to arrive at constant specific numerical parameters in these cases ; and in all 
instances he has been surprised by finding that, in well-formed shells, the 
ratios of the successive whorls have been specifically constant. In making 
these measurements, the points to be determined are three, viz. : — 1st, the 
ratio of elongation of the radius vector of the spiral ; 2nd, the degree of linear 
expansion of the generating figure in the successive whorls j and 3rd, the 
degree of translation or slipping of the spiral on the central axis. The 
second of these we may call the discoidal coefficient, and the third the heli- 
coidal coefficient. 
The Lower Races of Man. — Sir John Lubbock delivered an interesting 
address on this subject at Liverpool. Among the extraordinary points were 
those concerning marriage. Thus, the idea of marriage does not in fact 
exist in the Sandwich Island system of relationship. Uncleships, auntships, 
cousinsliips, are ignored, and we have only grandparents, parents, brothers 
and sisters, children, and grandchildren. Here it is clear that the child is 
related to the group. It is not specially related either to its father or its 
mother, who stand in the same relation as more uncles and aunts, so that 
every child has several fathers and several mothers. 
