26 



HAREU'ICKE'S SCIENCE-GOSSIP. 



the boreal fauna that it has no representative in 

 North America, since there are forms peculiar to 

 Northern Europe and Asia which are not American ; 

 yet I myself should be disposed to regard these as 

 belonging rather to the Germanic than boreal type — 

 as for instance, Li max cinereo-niger, which I had 

 formerly considered boreal. 



Another difficulty, and this a more serious one 

 than might be supposed, is that of distinguishing 

 which are the imported species in America. 



One might think that there was no doubt that 

 Vanessa atalanta was indigenous to America, yet 

 Harris asserts that it was introduced from Europe 

 with the common nettle, and considering that Pieris 

 rapa- was only introduced into Canada about 1S57, 

 and now occurs abundantly even to the Rocky 

 Mountains and Georgia, doing damage to the cabbage 

 crop estimated at thousands of dollars annually, it is 

 hard to prove the nationality of a species by its 

 present distribution. 



So much for the specific forms, but how is it in the 

 case of certain genera, such as Apatura ? The 

 European species of this genus are few, and the 

 several species in America are decidedly southern in 

 their distribution, A. alieia occurring from Texas to 

 Florida, A. celtis not farther north than Virginia, and 

 so on. This undoubtedly requires some explanation 

 other than that of boreal origin, especially as it is by 

 no means an isolated case, and the only one I have 

 to offer is the following. In the Isle of Wight there 

 are found fossil land-shells more nearly allied to 

 West Indian than any European forms, and from 

 this and other evidence it seems certain that ages ago 

 there was some connection between Southern-Europe 

 and what is now the West India region (Southern 

 Africa being at the time probably cut off by the 

 submergence of the central region) and a similar 

 fauna existed throughout. The glacial period 

 destroyed this fauna in Europe almost entirely — 

 Central Africa being under water it could not migrate 

 southward, and the American connection was cut off. 

 But a few species survived in the Mediterranean 

 region, and were the origin of Apatura in Europe, 

 and such shells as the Mediterranean Ttidora ferru- 

 ginea, allied to common West Indian forms.* 



I am at present situated in a district, the Rocky 

 Mountains of Colorado, peculiarly interesting from a 

 geographical distribution point of view. The high 

 mountain peaks, rising to over 14,000 feet, and 

 continuous to the Arctic regions of British America, 

 have been an easy pathway for the migration of 

 boreal species southward, while a very different and 

 un-European fauna occupies the lower regions, and 

 mingles with the others on the mountain-side. 



Of the forty-eight species of Mollusca ascertained 

 to occur in Colorado, no less than fifteen may be 



* And it is probable that the European genus ClausiHa mi- 

 grated to the West Indian and South American region during 

 the same period. 



considered specifically identical with British forms, 

 and nine others are very closely allied, while the 

 remainder belong to the peculiarly American fauna. 



The fifteen European species, besides being found 

 in Colorado, have a wide distribution and are doubt- 

 less native in America : J'itriua limpida (petluada) 

 is found in Massachusetts and Manitoba ; and its 

 variety angelicx, in Greenland ; Hyalina nitida occurs 

 in Michigan and Massachusetts ; H. viridula (radta- 

 tula) as far north as Alaska (W. H. Dall), and east as 

 Mass. ; Conulus chersinus (fulvus) is found in Ontario 

 and many other localities ; Helix pulchetla, var. 

 costata, ranges to Anticosti Islands, and the type 

 {hxvigata) is common in Canada ; Cochlicopasubcylin- 

 drica [lubrica) is abundant from Alaska to Mass. ; 

 Pupa marginata is found in Mass., where there also 

 occurs its variety edentula ; Succinea ovalis (pfeiffen) 

 is common in the eastern states and Canada ; Limnaa 

 stagnalis occurs in Manitoba, Ohio, &c, and there is 

 an American variety, speciosa, Zgk, of which I have 

 seen English specimens collected in Yorkshire ; * 

 Limiiaa palustris is universally abundant in the 

 Eastern States and Canada, and very variable ; 

 L. humilis (truneatuia, var.), is also generally dis- 

 tributed and common ; Physa hypnorum occurs in 

 Illinois, Ohio, Manitoba, &c. ; Planorbis parvus 

 (glaber) is a well-known eastern and Canadian species ; 

 as are also Pisidium abditum (pusillum) and P. variabilc 

 {fontinale, subsp.). 



There are, however, several species of European 

 mollusca which have been introduced into America, 

 and must on no account be confounded with the 

 boreal fauna, such as Helix Cantiana in Canada, and 

 Li max maximus (cinereus) in the northern, and Helix 

 terrains in the southern states. 



{To be continued.) 



THE WEATHER.f 



THIS is an excellent book which was greatly 

 needed. For many years observers have been 

 noting their observations of barometers and ther- 

 mometers, yet the "great mass of these observations 

 have been practically of but little use. 



A few years since we heard a great deal about " the 

 gay science." Most persons have mistakenly con- 

 sidered meteorology as the dismal science. Those 

 who carefully peruse Mr. Abercromby's book will 

 have no good excuse for still holding that opinion. 



The first three chapters, which form Tart I. of the 

 book, are elementary, being weather-science and 

 forecasting the weather. These chapters refer to 



* This variety differs from the type in its invariable tawny 

 colour, its decided, almost regular striation, narrower aperture, 

 outer lip less curved and not prominent, and its delicate clobely- 

 adherent white columellar callus. 



f " A Popular Exposition of the Nature of Weather Changes 

 from Day to Day," by the Hon. Ralph Abercromby, F.R.M.S., 

 etc. etc. (London : Kegan Paul & Co.) 



