NOTES. 139 



silhetana the black border ends almost abruptly on the costa, 

 leaving the costal area of the remainder of the wing pale. 



With regard to what I consider the principal distinguishing 

 character, namely, the termination of the lower extremity of the 

 black border of the fore wing, the difference will be appreciated 

 more clearly by examination of the accompanying figures. There 

 is, normally, a strongly marked inward extension of the black border 

 below vein 2, its inner edge dipping sharply down to the inner 

 margin. In hecahe this edge meets the inner margin either squarely 

 (figs. 9, 10), or turns inwards along the margin towards the base of 

 the wing (figs. 6 to 8). There may be, and very frequently is, a 

 small yellow point projecting into the black, simulating the condi- 

 tion characteristic of silhetana , but this incursion of yellow is always 

 above the actual margin, and is followed by a distinct though slender 

 tongue of black running inwards along the extreme margin. In 

 silhetana (figs. 1 to 5), on the other hand, the lower extremity of the 

 black border invariably turns outwards, and is subtended by a 

 distinct marginal extension of the yellow area. This is independent 

 of the cilia of the inner margin, which are always yellow, in both 

 species. This character may seem trivial, but is constant in long 

 series of bred specimens that I have examined. It may be unappre- 

 ciable to the naked eye, but is readily distinguishable with a lens, 

 and — in any case of doubt — may be corroborated by the other 

 characters mentioned above. The distinguishing characters may 

 be indicated, synoptically, as follows : — 



Terias hecabe. — Outer margin of fore wing entire. Marginal 

 area of costa distinctly black. Lower extremity of 

 black border not subtended by yellow. 



Terias silhetana. — Outer margin of fore wing distinctly crenu- 

 late. Marginal area of costa yellow. Lower extremity 

 of black border partially subtended by yellow. 



E. ERNEST GREEN. 



15. Large Parasitic Thread-worm in a Butterfly. — In January, 

 1912, I received from Mr. F. M. Mack wood a specimen of Danais 

 chrysippus, from which a thread- worm had emerged after Mr. Mack- 

 wood had prepared the butterfly for exhibition. The worm was 

 5| inches (130 mm.) long and • 6 mm. in thickness. As the worm was 

 in a shrivelHng up condition when I received it, I could not identify 

 it with any certainty. It has the appearance of an ordinary 

 nematode worm, but larval nematodes and larval gordiids, which 

 differ very little in appearance from the adult nematode, are also 

 found parasitic in insects. 



[Ed.] 



