THE GENUS DEMODEX. 23 



2. DEMODEX CANTS, Leydig, 1859. 

 (Plate I. figs. 4 & 5.) 



I). foUicuIorit7n, Tulk, Ann. Mag. Nat. Hist. 1844, vol. xiii. p. 75. 



D. canis, LeyiHg, Arch. Naturg. 1859, Jiilirg. i. vol. xxv. p. 345. 



D. folliculorum var. caninus, Mognin, J. Anat. Physiol. 1877, vol. xiii. p. 111. 



I), caninus, Canestrini, Prospetto dell' Acarofauna Ital. 1899, part 8, p. 9G6. 



9 . D. canis is an elongated species, being usually more than six 

 (sometimes up to seven) times as long as wide. The cephalothorax 

 (not including capitulum) is a little less than half the length of the 

 abdominal part of the body and is of moderate width. Abdomen long 

 and slender, gradually tapering to the posterior end, which is bluntly 

 y)ointed. Capitulum of moderate width, being widest at the base, where 

 it is slightly wider than long ; the two spines on its dorsal surface are 

 very short and pointed. 



d . Size very variable, specimens of this sex being sometimes much 

 shorter than females. Male sexual orifice situated above the interval 

 between the first and second legs. Penis rather long, slender, and 

 usually curved. 

 Egg spindle-shaped. 



Author's measurements : — 



Female. 



Totallength of body (incl. capit) 180--264/A 



Length of cephalothorax + capitulum ... — 



„ abdomen — 



Greatest width of cephalothorax 40 /* 



„ „ abdomen — 



„ „ capitulum (at base) ... 31 /* 



Length of capitulum 27 /* 



„ spines on capitulum 4 /*. 



Canestrini's measurements of D. canis are as follows : — 



Adult form. Njmph. Larva. Oviim. 



Totallength 302 /x 239 ft 137 /x 10 /n 



Length of cephalothorax . 110 /x • — — — 



„ abdomen ... 192 /x — — — 



Greatest width .... 45-55 jn 45 /x — 4 ^ 



Megnin gives the following measurements of B. canis : — 



Ovigerous Ist Ijarya 2nd Larva Nymph 



female. Male. (apodous). (hexapod). (octopod). 



Totallength of body . . . -BS-'SO mm. •22--25 •06--09 -11 -19 



Length of thorax .... "10 „ "OOo — — — 



Width „ .... -045 „ -045 (of body) •015--025 -032 -04 



Length of capitulum . . . '03 „ '03 — — — 



Width „ (at biise) . -ua „ -03 — — — . 



