xlviii LLOYD'S NATURAL HISTORY. 



sub-costal nervure at its base, so as to give it the appearance 

 of being an additional branch of the sub-costal. In several dark- 

 coloured species of Papilio^ &c., there is an appearance of lines 

 radiating from the base in the cell ; but this is delusive, and 

 only one Butterfly is known to me with the radial nervules 

 continued as nervures through the cell to the base of the 

 wings. This is Davidina armandi, Oberthiir, a rare and little 

 known Pieride from China and Thibet. On the hind-wings 

 there is only one radial nervule ; but some authors consider 

 the sub-costal nervure of the hind-wings to be unbranched, 

 and call the second branch (b. 2. of our figure) the upper 

 radial instead of the second sub-costal nervule. 



In most Butterflies the cell is closed by small cross-nervures 

 called disco cellular nervules (g. i,g. 2), but in the Nymphalina 

 and Morphince, the lower disco-cellular nervule is either slender 

 and rudimentary, as in our figure, or entirely wanting. In the 

 latter case the cell is said to be open. The cell is more fre- 

 quently open in the hind-wings, but very commonly in the 

 fore-wings a^so. The space between the cell and the hind- 

 margi.i is called the disc of the wing. In the Brassolince there 

 is a small additional cell above the base of the discoidal cell 

 of the hind-wings, called the pre-costal cell. 



Below the discoidal cell runs the median nervure, which is 

 always three-branched (d, d, d). In England the median 

 nervules (or branches of the median nervure) are generally 

 counted from above downwards ; but as they are thrown off in 

 succession from below, it would appear more correct to count 

 them from below upwards, as is generally done by the German 

 lepidopterists. In order to avoid any ambiguity, it is perhaps 

 better to call them the upper, lower and middle median nervules. 

 In many Nymphalina, there is a short branch thrown off down- 

 wards from the median nervure near its base, which Schatz and 

 Rober call the " spur." When it is continued downwards to 



