60 



Observations on Parasites and Parasitic Diseases 



Fig. 8. 



to the hair in such a manner as to form a very acute angle with it, 

 leaving just sufficient space to allow of the young louse grasping 

 the hair with its claws as it maks its escape from the e^^ by raising 

 the operculum at the larger end, thus securing its safety against 

 falling off and being lost. The empty ova-cases will remain 

 in sitit for a considei-able time after the birth of the young lice, 

 and sometimes lead to an incorrect conclusion that the animal 

 is still covered with "nits." They are, however, easily distin- 

 guished from perfect eggs on a slight examination. 



Lice of the Horse. 



It has already been explained that two varieties of the louse 

 are common to the horse — the Hcematopinus and the Trichodectes. 

 The former of these is much the larger. It is 'also darker in 

 colour and has a longer body and head than the other. Fig. 8 

 gives a very faithful representation of this louse, and shows the chief 

 peculiarities of its conformation, which will be the more apparent 

 if the figure be compared with that of the Trichodectes of the ox, 

 inserted at p. 63. The H(Bmatoj)inus Equi more frequently locates 



itself among the stiff hairs of the 

 tail and mane than the Trichodectes, 

 but it will nevertheless be often dis- 

 tributed over the entire body of the 

 animal. It is not easily dislodged 

 from its location in consequence of 

 its sucking -organ being inserted 

 into the skin for the purpose of ob- 

 taining its food. For this reason 

 Hoimatopini produce considerable 

 and persistent irritation ; and the 

 horse will rub himself so violently 

 to get rid of his tormentors as very 

 frequently to produce extensive ex- 

 coriations of the skin. From the 

 same cause his health will soon 

 suffer, and he will quickly fall away 

 in condition. Horses which are 

 neglected as to grooming and feed- 

 ing, or such as are suffering from 

 ill health, are, as is well known, 

 A'ery susceptible to attacks of lice. 

 Heematopini, however, are often met 

 with under the opposite circumstances ; and hence search should 

 be made for them in obscure cases of cutaneous irritation. We 

 have frequently found these lice on horses which were at the time 



Hocmatopinus Equi. Magnified. 



