402 Dr. T. A. Chapman on the 



on the mesothorax (comparison is with orbit ulus). The 

 metathorax to the 7th abdominal segment have each one 

 dorsal lenticle (on each side). Orhitulus has two on 2nd to 

 6th abdominal segment ; but the figure referred to shows 

 that there is a tendency to lose them even on orhitulus, as 

 evidenced by the 2nd abdominal segment having two on 

 one side and only one on the other. Two on the 1st ab- 

 dominal segment also is the rule in Plebeiids. Pyrenaica 

 has no lenticles on the 7th and 8th abdominal segments 

 or any marginal ones — a very unusual difEerence, not only 

 from orhitulus but from the usual Plebeiid pattern. The 

 crochets of the prolegs and claspers are two in number as 

 in orhitulus, and like it have one larger than the other, but 

 not at all so markedly. 



March 13th, 1915. — Three larvae found on principal 

 (dead) mass of Androsace. Put on living plants one looks 

 well, but two have been attacked and killed by Dipteron 

 larvae. 



April 24th. — No further larvae have been found to have 

 survived the winter. The one that looked well (13 iii.) 

 died when placed on a growing plant. 



The dipterous larvae are those of "a species of Sciara." 

 " They probably feed in the larval stage on decaying veget- 

 able matter, and will not interfere with vour lepidopterous 

 larvae " (J. S. Collin, in letter, Oct. 20, 1914). 



That the proper food of these Sciara larvae is decaying 

 vegetable matter is from my own observations unquestion- 

 able, but they also show that when they reach a quiescent 

 lepidopterous larva, in suitable conditions of moisture 

 and temperature, they attack and destroy it. 



Mr. Knight's drawings of the larvae in their hibernating 

 stage, PI. LXV, figs. 1 and 2, show how dark the larva is in 

 its autumnal stages, as compared with those of L. orhitulus, 

 which takes an autumnal colouring very much the same as 

 it has in its mature instars. 



This seemed to bring my investigations to an abrupt 

 termination, since it was practically out of the question to 

 think of visiting the Pyrenees in 1915. But a friend in need 

 is a friend indeed. Monsieur Rondou, though weighted 

 with various extra duties and anxieties owing to the war, 

 managed to devote a little leisure to finding the larva in 

 the spring, and generously sent me the five examples he 

 obtained. 



A portion of Monsieur Rondou's letter accompanying the 



