the Lepidopterous Family Cossidae. 



169 



other orders as the radial sir/or. This again divides into 

 (a) the common stalk of the second and third radials, and 

 (l>) the common stalk of the fourth and fifth. The latter 

 is of such importance in the Lepidoptera that it is necessary 

 to give it a special name, and I have termed it the chorda. 

 It is noteworthy that, although the original dichotomy is 

 often obscured, the second and third radials, that is, veins 

 10 and 9, always arise by a common stalk. The enclosed 

 space, completed by a bar or anastomosis between 9 and 8, 

 is identified by Mr. Tillyard with the discoidal cell, but as 

 that term has been used with a different sense in the 

 Lepidoptera, I have thought it wiser to retain for it the 



Fig. '22. Macrocytlara expressa, Lnc. 



name areole. When areole and cell coalesce to form what 

 I will call an areoccl, it is evident that the original stalking 

 of 9 and 10 is obscured, so that they appear to arise 

 separately from the areocel as in fig. 23. The media divides 

 into (a) the common stalk of the firsl and second median, 

 and (b) the common stalk of the third and fourth median; 

 between them is the median cell. Mr. Tillyard has shown 

 (I.e., p. 169) thai the fourth median has coalesced with the 

 tirst cubital, thus closing the lepidopterous cell, which has 

 hitherto been known incorrectly as the discoidal cell, but 

 may be conveniently spoken of as the cell; it of course 

 includes the median cell when that is present. 



While the ('omslock-Nccdliam system is, so far as our 



