The Origin of the Markings of Caterpillars. 201 



are of different ages, the first (Euphorbia^ &c.) 



being the youngest, and the last (Hippophaes) the 

 oldest of the genus. 



According to their phyletic age, the groups 

 follow each other in inverse order, the first being 

 Hippophaes, the second that of Zygophylli, the 

 third that of Livornica, the fourth that of Galii, 

 and the fifth and youngest that of Euphorbia. 

 Only in this last am I acquainted with the 

 complete development of one species, for which 

 reason I commence with this group, thus pro- 

 ceeding from the youngest to the oldest forms, 

 instead of taking the more natural course from 

 the simplest and oldest to the youngest and most 

 complicated. 



DEILIPHJLA EUPHORBLE, LINN. 



Some captured females were at once placed in an 

 enclosure about the size of a small sitting-room. 

 It was evident that they did not feel quite at home 

 under these conditions, frequently beating their 

 heads and wings against the tarlatan, but some of 

 them nevertheless laid eggs at the base of the 

 leaves of Euphorbia Cyparissias. The eggs 

 much resemble those of Chcerocampa Elpenor, 

 being spheroidal in form, but rather smaller, and 

 of a somewhat darker green. They were laid in 

 small clusters composed sometimes of as many as 

 seven, the single eggs being placed near together, 

 but never touching, and seldom at the point of the 



