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NATURE 
[ Marcu 21, 1907 
In No. zo (March -11) of the Comptes rendus M. 
Giacobini states that the comet is a round nebulous object 
of 20” diameter, having an eleventh-magnitude nucleus, 
and, apparently, a tail in position-angle 180°. 
SEARCH-EPHEMERIS FOR Comet 1900 III. (Giacopini).— 
In No. 4159 (March 7) of the Astronomische Nachrichten 
Herren Abold and Scharbe publish a search-ephemeris, 
extending from March 5 to April 2, for comet 1900 III. 
As the probable time of perihelion passage is very un- 
certain, they give three ephemerides, in which T is taken 
as May 5, June 8, and July 13 respectively, June 8 being 
considered the most probable. No perturbations have been 
taken into account, and as on March 13 the calculated 
brightness was but o-4 of that observed on February 15, 
igor, it is icared that the hopes of re-discovering this 
Object are but small. 
SoLAR OBSERVATIONS AT CatANnta.—In No. 2, vol. xxxvi., 
of the Memorte della Societa degli Spettroscopisti Italiani 
Prof. Riced publishes the summarised results of the solar 
ations made at the Catania Observatory during the 
third and fourth quarters of 1906. There was a marked 
decrease in the daily frequencies of spots, facula, and 
prominences during the fourth quarter as compared with 
the third, which, however, showed an increase in the daily 
frequency of all three phenomena on,comparison with the 
results of the second quarter. 
obser 
INTENSIFICATION OF *‘ CONTRAST,’’ BY MEANS OF A POLARI- 
scorpr.—Some interesting suggestions concerning the in- 
tensification of contrast in astronomical observations, by 
the employment of the polariscope, are made by Dr. Felix 
Biske in No. 2, vol. xxxvi. (February), of the Memorie 
delia Sdcieta degli Spettroscopistt Italiant. 
Dr. Biske points out that under certain conditions 
the atmosphere and positions of the body observed it 
possible to polarise the light received so that the ratio of 
the amount of light from the body to that of the sky is 
increased, thus rendering the details of the observed object 
more easily visible. It is suggested that by this means the 
observation of the corona whilst the sun is not. eclipsed 
may be facilitated, and that comets, the light from which 
often shows a fair amount of polarisation, may be observed 
more easily. Similarly the. planets Mercury. and. Venus 
and the moon may, under certain conditions, be observed 
when by the ordinary method this would be very difficult 
or impussible. 
Tue Minor Praner (588) [1906 T.G.].—In No. 4155 of 
the Astronomische Nachrichten,.Dr. Bidschof gives’ a new 
set of elements and an ephemeris for the minor planet 
(588), which, it will be remembered, is remarkable for 
its @xtraordinary aphelion distance, lying an astronomical 
unit beyond the mean distance of Jupiter. The elements 
are based upon observations made during 1906, and differ 
somewhat from those previously published by Dr. 
Berberich. This interesting object will be unfavourably 
situated for northern observers for several years, but it is 
to be hoped that the southern observatories will endeavour 
to keep it under observation. 
The present magnitude of the planet is about 15-0, and 
it was re-observgd by Prof. Wolf, in a position in fair 
accordance with Dr. Bidschof’s ephemeris, on January 22. 
of 
is 
RESEARCHES tN STELLAR PHOTOMETRY.—Under the title 
“Researches in Stellar Photometry during the Years 
1894 to 1906,’’ made chiefly at the Yerkes Observatory, 
the Carnegie Institution of Washington has published 
a beautifully prepared and illustrated volume contain- 
ing the results of Mr..J.. A. Parkhurst’s careful and 
systematic study of twelve’ variable stars having long 
periods and faint minima. The observations were 
carried out first with a 6-inch reflector, then with 
a 12-inch refractor, and finally with the 4o-inch re- 
fractor of the Yerkes Observatory. Argelander’s method 
of comparison was employed, and during the later years 
the comparison stars- were carefully standardised with a 
Pickering equalising wedge-photomcter. In addition to 
the tabulated results giving the individual observations of 
the variable and of the comparison stars, Mr. Parkhurst 
gives the complete light-curve, for the period of obsery- 
ation, of each variable, and a plate reproduction of a 
NO. 1951, VOL. 75 | 
| the 
photograph showing the region surrounding each star; the 
majority of these are on the scale of 1 mm.=13!s5 
(approx.).. As an example of an attack on an important 
phase of the sidereal problem, the volume is almost unique 
in the wealth of detail it contains and the lavish manner 
in which the results are presented. 
MARSUPIALS OR CREODONTS? 
HE vexed question as to the real affinities of the 
marsupial-like carnivores of the Santa Cruz beds of 
Patagonia has once more been brought prominently to the 
front by the appearance of a memoir on their osteology 
and dentition in the fourth volume of the reports of the 
Princeton Expedition of 1896-9 to Patagonia. In this 
memoir the author, Mr. W. J. Sinclair, takes up a very 
decided position, remarking that these so-called sparasso- 
donts (as represented by Prothylacinus, Borhyatna, Amphi- 
proviverra, &c.) possess a number of characters either 
peculiar to marsupials or common to that group and only 
a few other orders. ‘These, it is urged, will convince the 
reader that sparassodonts are true carnivorous marsupials, 
not worthy of even separate subordinal rank. ~ Mr. 
Sinclair goes, however, even farther than this, and con- 
siders. himself justified in including the Patagonian 
carnivores in -the same family group as ,the existing 
Tasmanian pouched wolf or thylacine, which he separates 
from the Dasyuridze under the designation of Thylacinidz 
(or Thylaeynidz). It is added that, *‘ although there is 
sufficient similarity in structure to warrant placing the 
Patagonian and Tasmanian thylacines in the same family, 
it must not be inferred that the existing genus is the direct 
descendant of. its extinct South American forerunners. 
The study of the group has failed to show a closer relation- 
ship than probable descent from a common Santa Cruz 
ancestor. While retaining the fundamental family 
characters, both lines have diverged, and in some) respects 
the Santa Cruz forms are more advanced than the existing 
genus.”” 
Among the structural features on which the author relies 
as evidence of the marsupial nature of the Patagonian 
fossils are the dental formula, the reduction in the number 
of successional cheek-teeth, the inflection of the angle of 
the lower jaw, a number of peculiarities in the conform- 
ation .of the skull, and the perforation of the transverse 
process of the seventh cervical vertebra by the arterial 
canal. On the other hand, vacuities in the bony palate 
and epipubie (marsupial) bones, both of which are 
characteristic of most existing marsupials, are wanting. 
As regards the dental formula of the cheek-teeth, this, 
in the opinion of Dr. J. L. Wortman (Amer, Journ. Sci., 
vol, xi., p. 336, 1901) and the present writer, is identical 
in the sparassodonts, carnivorous marsupials, and creo- 
donts, and is, therefore, of no importance, except to in- 
dicate the mutual relationship of all these three groups. 
By all zoologists of the present day it is, I believe, admitted 
that the reduction of the replacing teeth in modern mar- 
supials to a single pair of premolars in each jaw is a 
secondary feature, so that the presence of a larger number 
of such teeth in the sparassodonts indicates the more 
primitive nature of those mammals, and one allying them 
to: creodonts. Some of these sparassodonts differ, how- 
ever, from all the more. typical representatives of the 
latter group in having four, in place of three, pairs of 
upper incisor teeth, and thus resemble carnivorous mar- 
supials ; but since this feature is likewise regarded by Dr. 
Wortman (op. cit., p- 335) as of secondary origin, it is 
no bar to the derivation of sparassodonts from creodonts, 
while it indicates that the latter are not likely to be the 
descendants of the former. As the author himself regards 
the presence of vacuities in the palate and the inflection 
of the lower iaw as being likewise secondary features in 
marsupials, all these lines of evidence point to the con- 
clusion that creodonts are the most primitive of the three 
groups under consideration. 
It follows from this, on the author's assumption that 
Patagonian carnivores are thylacines, that palatal 
vacuities have been independently developed in several 
families of existing marsupials, and a similar argument 
will hold good with regard to the reduction of the 
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