SCIENCE- G OS SIP. 



363 



CLASSIFICATION OF BRITISH TICKS. 



By Edward G. Wheler. 



THE Ixodidae have received so little considera- 

 tion at the hands of British naturalists 

 that there does not exist amongst our literature 

 any classification of the family having pretension 

 to accuracy or completeness. This may be sufficient 

 to account for the fact that when inviting 

 coiTespondence last year, through the columns of 

 Science -Gossip, I did not receive any reply from 

 a fellow-countryman who had made a serious 

 attempt to study the British ticks ; though I 

 have been favoured with much kindly assistance 

 from correspondents who had turned their atten- 

 tion to foreign species. 



There seems no doubt that the best classification 

 of the genera, giving descriptions of the known 

 species, is that con- 

 tained in a very care- 

 fully compiled series of 

 articles in the " M6- 

 moires de la Societe 

 Zoologique de France" 

 for the years 1896-97- 

 99 (vols, ix., x. and 

 xii.). These articles 

 were written by M. G. 

 Neumann, Professeur a 

 l'Ecole |veterinaire de 

 Toulouse, and are en- 

 titled " Revision de la 

 famille des Ixodides." 

 These papers are out of 

 print, and are not likely 

 to fall readily into the 

 hands of an English 

 reader. 



It is with the object 

 of popularising the sys- 

 tematic study of the 



ticks that I venture to print the following resume 

 of M. Neumann's classification, giving copies of 

 such of his figures as may assist in explaining 

 the letterpress ('). To condense as much as 

 possible, I have confined my descriptions, which 

 are in great part taken from those of M. Neumann, 

 to the more salient characteristics that may pro- 

 bably suffice for identifying the sub-family and 

 genus to which a specimen may belong. To 

 these are added remarks on the number of 

 known species in each genus, a description of 

 those which have been identified in this country, 

 a list of synonyms, and other points of interest. 

 Most of the characteristics referred to are such as 

 may be examined readily without having recourse 



(1) The illustrations copied are figs. 5, 7, 10, 18, 19, 21 

 and 24. 



to any more powerful magnifier than a pocket 

 lens. 



A short description, with a diagram (fig. 1), of 

 the various parts of a tick referred to in this 

 paper may assist readers in following Professor 

 Neumann's classification. 



Ticks pass through four stages in their exist- 

 ence : the egg, the larva, the pupa or nymph and 

 the adult. In the larval, pupal and adult female 

 stages the body consists of a highly distendable 

 cuticle. This, in the sub-family Ixodinae, is partly 

 covered by a hard scutellum, or shield, on the back, 

 and is provided with a false head, or capitulum, 

 that carries the palpi, and the mouth organs, con- 

 sisting of a hard chitinous labium or hypostorne 

 provided with a tube 



S y 





Fit:. 1. 

 Nomenclature of External Parts op Sheep-tick. 



for the suction of blood, 

 and armed with rows of 

 barbs for clinging on 

 to the flesh of the host. 

 On each side are situ- 

 ated the mandibles, also 

 called chelifers, or cheli- 

 cerae. They are re- 

 tractile, and doubtless 

 serve to cut a slot in 

 the skin to make a pas- 

 sage for the insertion 

 of the labium, and 

 afterwards to force it 

 into the flesh of the 

 host. For these pur- 

 poses the chelifers are 

 furnished with a series 

 of teeth or hooks. Col- 

 lectively these organs 

 are called the rostrum. 

 The adult male is 

 similar, but he has a shield that, with the excep- 

 tion in many cases of a narrow margin, covers the 

 whole of the body. The latter is incapable of 

 being much distended by the suction of the 

 host's blood. In the sub-family Argasinae these 

 shields are altogether absent. In the larval stage 

 ticks have but six legs, but in all other stages 

 eight legs. 



In adults the sexual organ is situated far forward 

 between the haunches of the legs ; behind it is the 

 anus, usually surrounded in part by a groove, and 

 on each side, near the fourth pair of legs, is placed 

 a stigmal plate or peritreme for respiration, in the 

 centre of which is the stigma. The plates are absent 

 in the larval state. There is reason for believing 

 that the sexual organ of the male above referred 

 to is either immature or obsolete in certain, if not 



