Physiology o/'IIsematopinus tcnuirostris, Barm. 81 



Ilcematopinus tenuirostris^ Burm. 



(Pediculus vitulij Linnej Hrematopinus vituliy Stephens 

 and Denny ; Pediculus oxyrhynchus, Nitzsch ; Pediculus 

 tenuirostris, Burmeister.) 



External Anatomy. 



Hcematopinus tenuirostris, or the Sharp-headed Ox-louse, 

 lias a rather elongated and elegant shape (PL III. fig. 1). Its 

 colour throughout is a shining brown, u chestnut and shining ? ' 

 as Denny (10, p. 31) correctly calls it, passing into dark 

 brown in the claws. The head and thorax show a light grey 

 tinge, while the abdomen presents a tint which it is difficult 

 to describe, indicated by Linn£ (1, p. 476) as u ctbruleo-fusco," 

 by Giebel (13, p. 43) as " dirty bluish violet." This shimmer 

 is due to the stomach shining through, and varies according 

 to its degree of fulness. Like all the species of the genus 

 HfematopinuSj our animal presents a body distinctly divided 

 into head, thorax, and abdomen. 



The head is longish oval. The antennas, which are arti- 

 culated to the sides of the head about the middle, divide it 

 into two parts. The anterior, the forehead (frons) has a 

 length of # 214 millim.* Its sides, which are gently curved, 

 converge to a point from the antennae At the apex the 

 sheath of the rostrum, 0*027 millim. long, projects as an ob- 

 tuse process. The hinder part, measuring 0*261 millim. in 

 length, diminishes scarcely perceptibly behind the antennae, 

 then becomes somewhat wider, and thence to the thorax shows 

 nearly parallel temporal margins, so that the middle head 

 (synciput), or the part of the head situated between the temples 

 (tempora), appears nearly rectangular. The hind head (occi- 

 put) penetrates like a wedge into the thorax. The notch 

 on each side at that part of the head where the antenna* are 

 seated (excisura or sinus orbitalis, or orhitd) is very small. The 

 head has its greatest breadth, 0256 millim., a little behind 

 the antennas ; between the antennae its greatest breadth is 

 0*203, and in front of them 0*163 millim. In the anterior 

 part of the head are situated the buccal organs, in its hinder 

 part the cerebral ganglion and the very small and not easily 

 perceptible eyes 7 the position of which, however, is always 

 indicated by a weak bristle placed immediately above them. 

 The whole head is traversed from before backward by the 

 oesophagus and the tracheae of the head. The antennae 



* The measurements are always taken from the mean, :md relate, where 

 not otherwise stated, to the £, as the mure abundant. 



