PRELIMINARY NOTE ON SOME EXPERIMENTS 

 WITH A POLYMORPHIC PHASMID. 



By J. C. F. FRYER, M.A., 



Fellow of Gonville and Gains Coller/e, Balfour Student in the 

 University of Cambridge. 



Among a large brood of " stick-insects," reared from the egg by 

 Mr E. E. Green, Government Entomologist in Ceylon, it was noticed 

 that, though the ^/"s were all similar, two distinct types of ^ were 

 present. The case seemed to merit a detailed investigation, the 

 preliminary results of which are presented in the following notes. 



The insect in question is a typical apterous "stick-insect," the 

 general appearance of which can be seen at once from the plate 

 (Plate III); the special characters studied in the experiments were 

 firstly the colour of the adults, and secondly the presence or absence 

 of pointed conical horns on the head (Figs. 4, 5). With respect to 

 these characters the ,/ never varies ; it never has horns, is always 

 dark chocolate brown in colour and is a much more slender insect 

 than the female. In the original brood two forms of $ were observed, 

 the one being horned and green in colour, while the other was hornless 

 and yellow. 



This dimorphism in the ? in relation to the presence and absence 

 of horns leads to a difficulty in determining the specific identity of the 

 insect. It belongs to the division Clituiunini of Brunner v. Wattenwyl 

 and Redtenbacher, but falls into the genus Glitumnus Stal. or Ciinicidina 

 B. V. Watt, according to whether the % is without horns or possesses 

 these appendages. Both Westwood in his Catalogue of the Phasmidae' 

 and Brunner v. Wattenwyl and Redtenbacher in their celebrated 



' Catalogue of Orthopterous Insects, Phasmidae, p. 9, PI. 5, Fig. 2. 



