605 
WA ROR 
| April 26, 1883 
From the verticality, linear form, and condition of atmo- 
sphere I was led to remark at the time to my companion that 
the phenomenon appeared more of the nature of parhelia than 
referable 10 the zodiacal light. An intensely cold easterly wind 
encountering ocean-warmed airs to the westward would not 
improbably lead to the ice-molecule condition of atmosphere 
now assumed to be associated with the occurre ce of parhelia. 
It may be added (though of little probable significance) that 
the time corresponded roughly with the time of high water along 
that coast. D. J. Rowan 
Kingstown, April 24 
On the Value of the ‘‘ Neoarctic” as one of the Primary 
Zoological Regions 
PERMIT me to make a few remarks relative to Mr. Wallace’s 
criticisms (NATURE, vol. xxvii. p. 482) of my paper on ‘‘ The 
Value of the Neoarctic as one of the Primary Zoological Regions.” 
Briefly stated, it is maintained in the early portion of this paper 
(1) that the Neoarctic! and Palzarctic faunas taken individually 
exhibit, in comparison with the other regional faunas (at least 
the Neotropical, Ethiopian, and Australian), a marked absence 
of fosttive distinguishing characters, a deficiency which in the 
mammalia extends to families, genera, and species, and one 
which, in the case of the Neoarctic region, also equally (or nearly 
so) distinguishes the reptilian and amphibian faunas; (2) that 
this deficiency is principally due to the circumstance that many 
groups of animals which would otherwise be peculiar to, or very 
characteristic of, one or other of the regions, are prevented from 
being such by reasoa of their being held in common by the two 
regions ; and (3) that the Neoarctic and Palzearctic faunas taken 
collectively are more clearly defined from any or all of the other 
faunas than either the Neoarctic or Palzearctic taken indi- 
vidually. 
In reference to these points Mr. Wallace, while not denying 
the facts, remarks: ‘‘ The best division of the earth into zoo- 
logical regions is a question not to be settled by looking at it 
from one point of view alone; and Prof. Heilprin entirely omits 
two considerations—peculiarity due to the absence of widespread 
groups and geographical individuality.” Numerous families and 
genera from the classes of mammals and birds are then cited as 
being entirely wanting in the western hemisphere, and which— 
in many cases almost sufficient to ‘‘ characterise the Old World 
as compared with the New ”—‘‘ must surely be allowed to have 
great weight in determining this question.” No one can deny 
that the ab ence from a given region of certain widespread 
groups of animals is a factor of very considerable importance in 
determining the zoological relationship of that region, and one 
that is not likely to be overlooked by any fair-minded investi- 
gator of the subject. But the value of this wegztive character 
afforded by the absence of certain animal groups as distinguish- 
ing a given fauna, is in great measure proportional to the extent 
of the positive character—that furnished by the presence of 
peculiar groups—and indeed may be said to be entirely depen- 
dent on it. No region can be said to be satisfactorily distin- 
guished from another without its possessing both positive and 
negative disti:guishing characters. Mr. Wallice has 1n his 
several publications laid considerable stress upon the negative 
features of the Neoarctic fauna as separating it from the Palz 
arctic or from any other, but he has not, it appears to me, suf- 
ficiently emphasised the great lack, when compared to the other 
faunas, of the positive elewent, the consideration of which is the 
point aimed at in the first portion of my paper, and which has 
led to the conclusions already staied, that only by uniting the 
Neoaretic and Palzarctic resions do we produce a collective 
fauna which is broadly distinguished by both positive and nega- 
tive characters from that of any other region. - If, as Mr. 
Wallace seems to argue, the absence from North America of 
the ‘families of hedgehogs, swine, and dormice, and of the 
genera Meles, Equus, Bos, Gazella, Mus, Cricetus, Meriones, 
Dipus, and Hystrix” be sufficient, as far as the mammalian fauna 
is concerned, to separate that region from the Palzaretic, could 
not on nearly equ lly strong grounds a separation be effected in 
the Palearctic region itself? Thus, if were to consider the 
western division of the Palearctic region, or what corresponds 
to the continent of Europe of geographers, as constituting an 
* In the paper under consideration I have given what appear to me 
satisfactory reasons for detaching certain portions of the South-western 
United States from the Neoarctic (iny Trarctic), and uniting them with the 
Neotropical region. 
independent region of its own, it would be distinguished from 
the remainder of what now belongs to the Palzarctic region by 
negative characters probably fully as important as those indicated 
by Mr. Wallace as separating the Neoarctic from the Palzearctic 
region. The European mammalian fauna would be wholly 
deficient, or nearly so, inthe genera Zguus, Moschus, Camelus, 
Poephagus, Gazella, Oryx, Addox, Sarga, Ovts, Lagemys, Tamias, 
in several of the larger Fel:de, as the tiger and leopard, and in 
a host of other forms. A similar selection could be made from 
the class of birds (among the most striking of these the Phasian- 
ide and Struthionida), but it is scarcely necessary in this place 
to enter upon an enumeration of characteri-tic forms. Divisions 
of this kind, to be chara*terised principally or largely by nega- 
tive faunal features, could be effected in all the reyions, and in 
some instances with probably more reason than in the case under 
discussion. 
But the question suggests itself, What amount of characters, 
whether positive or negative, or both, is sufficient to distinguish 
one regional fauna from another ? Mr. Wallace states: ‘* There 
runs through Prof. Heilprin’s paper a tacit assumption that there 
should be an equivalence, if not an absolute equality, in the 
zoological characteristics and peculiarities of all the regions.” 
Is it to be inferred from this quotation that Mr. Wallace recog- 
nises no such general equivalence? Is a region holding in its 
fauna, say, from 15 to 20 per cent. of peculiar or highly charac- 
teristic forms to be considered equivalent in value to one where 
the faunal peculiarity amounts to 60 to 80 per cent? If 
there be no equivalence of any kind required, «hy not give to 
many of the subregions, as now recognised, the full value of 
region ? 
Surely, on this method of looking at the question, a province 
could readily be raised to the rank of a full region, In the 
matter of geographical individuality little need be said, as the 
circumstance, whether it be or be not so, that the ‘‘ temperate 
and cold parts of the globe are necessarily less marked by highly 
peculiar groups than the tropical areas, because they have been 
recently subjected to great extremes of climate,” does not affect 
the present issue, seeing that the peculiarity is greatly increased 
by uniting the two regions in question ; nor does it directly affect 
the question of the \eoarctic-Palzearctic relationship. 
The second part of my paper deals with the examination of 
the reptilian and amphibian faunas, and the general conclusion 
arrived at is: ‘‘that by the community of its mammalian, 
batrachian, and reptilian characters, the Neoarcric fauna (exclud- 
ing therefrom the local faunas of the Sonoran and Lower Cali- 
fornian subregions, which are Neotropical) is shown to be of a 
distinctively Old World type, and to be indissolubly linked to 
the Palearctic (of which it forms only a lateral extension).” 
Towards this conclusion, which, it is claimed, is also borne out 
by the land and freshwater mollusca and the butterflies among 
insects, I am now happy to add the further testimony of Mr. 
Wallace (overlooked when preparing my article respecting the 
Coleoptera (‘ Distribution,” ‘‘Encycl. Britann.” gth ed. vii. 
p- 274). 
As regards the name ‘“‘ Triarctic,” by which I intended to 
designate the combined Neoarctic and Palzearctic regions, and 
which may or may not be ‘‘ somewhat awkward,” I beg to state 
that, at the suggestion of Prot. Alfred Newton (who, as he 
informs me, has arrived from a study of the bird faunas at con- 
clusions approximately identical with my own), it has been re- 
placed by ‘‘ Holarctic.” In conclusion, 1 would say that, while 
the views enunciated in my paper may not meet with general 
acceptance at the hands of naturalists, it is to be hoped that they 
will not be rejected hecause they may ‘‘open up questions as 
regards the remaining regions which it will not be easy to set at 
estes ANGELO HEILPRIN 
~ Academy of Natural Sciences, Philadelphia, April 6 
Mock Moons 
A LITTLE before midnight on Monday, the 16th inst., the 
moon, being nine days old and about 30° above the western 
horizon, was surrounded by an unusual halo. Its radius was 
certainly more than the normal 22°. By careful estimation I 
judged it to be about 30°, the lower edge resting on the horizon. 
On the right and left limbs of the ring were very distinct bright 
patches, rather broader than the ring itself, and slightly elon- 
gated outwards. The right-hand patch appeared to be in its 
normal position on a line passing through the moon, parallel 
with the horizon, but the left-hand patch was distinctly elevated 
