lepidopterotis larvce and jMjxe. 155 



dark markings (with a median dark line in this species), 

 " The whole forming a marking which perhaps makes 

 the caterpillar ajipear still more alarming to its foes." 

 In the figure of the larva of C. elpenor in the last stage 

 (fig. 23, pi. iv., of the English translation), Weismann 

 shows that the black line which forms the lower margin 

 of the subdorsal is widened into a black patch upon the 

 third thoracic segment, and curves upwards round the 

 posterior extremity of the white subdorsal line to meet 

 the upper dark margin. The figure does not indicate 

 the undoubted fact that this patch which surrounds the 

 end of the white line is much blacker than the rest of 

 the dark margin. The upper margin is also darker 

 upon this segment, although the difference is less marked 

 than in the case of the lower margin. The "mirror" 

 of the eye is formed by the posterior end of the white 

 subdorsal ; the " ground area " by the black patch which 

 encircles the former in every direction except anteriorly' ; 

 there is no trace of a " nucleus," as in the well-known 

 eyes on the first and second abdominal segments. When 

 the larva assumes the terrifying attitude, and the head 

 and thoracic segments are telescoped into the first 

 abdominal segment, the swollen anterior end of the body 

 is abruptly truncated, and, when looked at from the 

 front, appears as a liattish circular face marked by deep 

 concentric furrows, which are the lines between the 

 segments, and between the annuli which are upon the 

 latter. The result of these deep furrows and of the 

 shortening of the subdorsal is to render the latter and 

 its dark margins inconspicuous, except in the posterior 

 part of their length, where they become broadened, 

 shortened, and rendered very prominent as two eye-like 

 marks, one on each side of the median line and towards 

 the upper margin of the face-like extremity of the larva. 

 Their position is therefore exactly that which better than 

 any other produces the effect of eyes upon an enemy 

 approaching from the front. Although the white 

 "mirror" is not completely encircled by the "ground 

 area," no impression of imperfection is produced, and 

 the effect of the furrows and contraction is such as not 

 to suggest the continuity of the eye-like parts of the 

 subdorsal and its margins with the rest of these markings 

 on the anterior thoracic segments. My friend Professor 

 Meldola was staying with me at the time when I was 



