THE GENUS DEMODEX. 21 



Larvcc. — Slender elongated larv.B of this species are sometimes met 

 with, and they may reach a great length (430 (^), being up to 8|- times 

 as long as their greatest width ; three pairs of ridge-like lateral 

 appendages (epimera) are present, and they bear the usual pair of tiny 

 spinulose tubercles; the outer side of each epimeron projects as a 

 strong spine or process. Smaller specimens of this slender larval 

 form apparently sometimes have only a single median tubercle on the 

 epimeron instead of two. Nearer the middle ventrally there are the 

 three usual pairs of lobes, the anterior pair being especially minute, 

 whilst the last (posterior pair) are somewhat longer than the middle 

 pair. Capitulum well defined, each of the three segments projecting a 

 little laterally so as to form a short but distinct spine. G. Simon figures 

 a larva of this elongated type, but makes the mistake of showing the 

 legs as segmented. It is also figured by Erasmus Wilson (his figs. 24, 

 26, & 27). This elongated type of larva could easily be mistaken for 

 the nymph, but it has only three pairs of appendages. It is remarkable 

 that larvse should reach such a comparatively large size. The smaller 

 larval and nymphal stages of this species have not been examined by 

 the'author, but they are figured in Erasmus Wilson's paper. 



Ni/mphs. — Elongated nymphal forms very similar to the larvae in 

 general appearance are sometimes found, but they have four pairs of 

 lateral appendages and four pairs of ventral discs (instead of only three 

 as in larvae). The epimera show traces of segmentation, being divided 

 into two by a transverse line ; the usual pair of spinulose tubercles are 

 present on their surface. Some of these elongated nymphs are nearly 

 seven times as long as their greatest width. A specimen containing a 

 fully developed adult measures about 340 (/j, but still larger deulonymphs 

 may be met with. 



Author's measurements : — 



Female. Male. 



Total length of body (iucl. capit.) . . 270-440 ;u Elongated si>eciiuens . 280^ 



Small male with tail . 170 /i 

 „ „ with no tail 100-210 /n 

 Length of cephalothorax + capitulum . ,95^ 85 /^ 



abdomen 170-340^ 200 /i 



Greatest width of cephalothorax , . . 50-.5G/i 47-50^ 



„ „ abdomen 49-58 /x 46 /» 



„ „ capitulum (at base) . 40 ^ 33 u 



length of capitulum 24 /i 21-22 /i 



l.ength of .spines on capitulum (about) .3^ 3« 



