SCIENCE-GOSSI/\ 



limy hnpcd lo I'liid J'linhiniiis cipol/o \n onx lirilish 

 mountains, but uxpeiiL'ncc has taught us that the 

 search is fruitless, although uur niumitains difler but 

 little in aspect from many of those on the Continent, 

 on which /'. apollo, Colias /'Iticoiiionc &\\& C. palaciio, 

 besides many species of Erchia and Argyiiinis are 

 common, which are here altogether unknown. 



LOCAI.IZATIOiN. 



There is a remarkable phenomenon which may be 

 observed even amongst our British Butterflies ; 

 namely that of the localization of species, as for 

 instance in the case of Papilio inachaon^ Lycaeim 

 ario/i, Mdilaca ciiixia, Hespcria actaeon, Cyiiopides 

 palaemon, etc. We know it is of little use to look for 

 these species, except in the special localities chosen by 

 them as their habitat. We also know that many 

 British species, although widely distributed are only 

 to be looked for in certain circumscribed localities. 

 As examples of these, we may cite such species as 

 Argyiiiiis paphia, and A. aglaia, Alelanargia galafea, 

 Hespcria comma, etc. Such are certainly not un- 

 common species, but are not abundant everywhere. 

 Taking the Palaearctic Region as a whole, we find 

 many species localized in a remarkable manner. In 

 many cases we can see that this is the consequence of 

 the local nature of the food plant of the larva. Hyperm- 

 iicstra helios depends upon the presence oiZygophylhim 

 lun-omanum, Charaxes jasius on Arbutus tmcdo. 



Lihyllua celt is is only found where Celt is mistral is is 

 wild. Often however there is not anything to account 

 for the localization of species ; the food plant being 

 frequently aljundant in places where the butterfly is 

 absent. Two European butterflies Zegris euphcnie 

 and Satynis liippolyte are found only in AndaUisia and 

 in South Russia. It is" impossible to account in an_\- 

 satisfactory manner for their isolation in such widely 

 separated localities. . 



The selection of food plants is, in itself, one of the 

 unexplained mysteries of nature, nevertheless il is an 

 undisputed fact. Some larvae are very exclusive in 

 their food, others are almost omnivorous, the latter 

 as a rule are those of common and widely distributed 

 species. In respect of food plants, there is often a 

 relation of Zoological to Botanical groups. The 

 larvae of 'J'liais and some allied genera are found 

 exclusively on plants of the genus Aristolochia : 

 Parnassius on Saxifrages and Crassulaceae ; the 

 genus Pieris and its allies, select plants of the order 

 Cruciferae ; Colias, Leguminosae ; Vanessa, Urti- 

 caceae ; Argynnis, Violaceae ; the Satyridae on various 

 species of grasses. There is as I have stated above a 

 hidden law of nature which governs this selection ; 

 what the effect of it is, upon the configuration of the 

 various groups and species, we do not know, but it 

 is possible that such an effect does exist. 

 f To be contimted.) 



TICKS AND "LOUPING-ILL." 



By E. G. Whelek. 



'X'HE British Ixodidae, or Ticks, are likely to 

 -*■ receive far more attention in the future 

 than in the past. Hitherto they have been almost 

 entirely neglected, and it is impossible to obtain 

 much information concerning them. No syste- 

 matic classification or description of any of the 

 British species in their various stages of develop- 

 ment appears to have been attempted. 



It seems to have been proved beyond doubt, by 

 the researches of Messrs. Greig-Sniith, Meek, and 

 others (see the "Veterinarian," May, 1S97, etc.), 

 that through the agency of ticks, a bacillus is intro- 

 duced into the systems of the hill sheep of the 

 Scottish Borders. This is the cause of the very 

 fatal disorder known in the North by the name of 

 " Louping-Ill," or "Trembling." The disease is 

 analagous to the Texas and Queensland cattle 

 fevers, also to the Australian sheep disease, all 

 of which are similarly traced to the attacks of 

 ticks. It is possible that other diseases may 

 eventually be proved to be caused in a like 

 manner. The life-history of these pests has there- 

 fore become a matter of much economic import- 

 ance, as it may be hoped that, when their habits 

 are thoroughly known, some method may be 

 found, either for preventing, or at least minimis- 

 ing, the damage they occasion. 



The following notes have been collected with 

 this object during the last few months, and some 

 descriptions will be given of the various stages of 

 three of the commonest species. — Ixodes reduvitcs, 

 1. hexago}ius, and /. plumbetis (^). The first of 

 which is probably chiefly concerned in causing 

 Louping 111. 



The genus Ixodes, or true tick, must not be con- 

 founded with the " Sheep Spider Fh'," or " Ked," 

 to be found on almost every sheep, and often 

 erroneously called the sheep tick. This is a wing- 

 less fly, allied to the New-Forest fly, the grouse-fly, 

 etc., and has nothing in common with the Ixodes, 

 either in habits or appearance. 



Ixodes may be described as follows : — An ovi- 

 parous insect (-) passing through the stages of 

 larva, pupa, and adult. The females live by suck- 

 ing the blood of mammalia, by which their bodies, 

 covered with a tough, membranous, semi-trans- 

 parent cuticle, are capable of great distension in 

 all stages of their existence. The adult males do 

 not distend, though they equally attack their hosts. 



(^) I am indebted to Prof. Neumann of Toulouse for the 

 names of the first two species, and to Mr. R. I. Pocock for 

 the third, taken from a named specimen in the British 

 iluseum. There are, however, doubts as to its accuracy. 



(^) It is not a tnte insect, having: in its maturer stages of 

 life eight legs, and allied to the Arachnidae, or Spiders. 



