( xlv ) 



Dr. Mortensen, had made no special study of mimicry and 

 his " observations are made entirely independently, so to say 

 unintentionally, without any preconceived ideas or wishes to 

 find instances of mimicry, protective resemblance or the like." 

 This detached attitude gave a special value to the conclusions 

 on the extraordinary phenomenon of the " double " or " false 

 head " in Lycaenidae, reached by the author during his resid- 

 ence in the island of Taboga, Panama, Nov. 1915-Feb. 1916. 

 Here he observed on the hind-wings the antenna-like tails, 

 the associated eye-spots, the alternate movements, the out- 

 ward bent lobe of certain species giving " the most wonderful 

 likeness to a real broad head," and, with all this, the incon- 

 spicuous real head and motionless real antennae. The 

 Lycaenids observed — at least a dozen species — were never 

 seen to rest head downwards but always horizontally on 

 leaves or flowers. The species figured were Thecla acts, 

 Drury, T. jihaleros, L., T. battus, Cram., T. marsyas, L., 

 together with four unnamed species. The Nymphaline 

 Gynaecia dirce, L., also figured, was stated always to rest head 

 downwards, usually on tree -trunks, and seeing it in its natural 

 position " one cannot resist the impression that it is the head 

 turned upwards, and that the meaning of it must be, that 

 lizards are thereby induced to direct their attack at this 

 non-vital part." Attention was also directed in this species 

 as well as in certain Lycaenids such as Thecla phaleros and 

 T. battus to the convergence of the lines of the under surface 

 pattern towards the " false head " and the greater brightness 

 of the colouring near it. Hence " the eye is involuntarily 

 directed towards this spot. This is a curious analogy to the 

 honey guides in flowers." 



Although the author accepted the interpretation that 

 enemies are thus " induced to attack this non-vital part, 

 while the butterfly escapes with the loss only of a part of its 

 wings, unessential for the flight," he never found a specimen 

 "with the fake head partially or completely bitten off"— 

 perhaps a consequence, as he suggests, of the limited vertebrate 

 fauna of so small an island; for precisely these injuries were 

 known to be very common, and dozens of examples from all 

 kinds of localities existed in the Hope Department. 



