46 BUTTERFLIES OF THE RIVIERA 



ground colour greenish-blue throughout the whole 

 area between the base and the hind-marginal row of 

 black spots. Rare. 



OBSERVATION. On June 23 rd 1890, I caught four 

 specimens of the typical Arion, in the first-mentioned 

 locality, (one of them was a male and three were 

 females). They were all fresh except one, a 5. 



They were captured in a little field, on the west 

 side of theVallon near the entrance from the high road. 



I subsequently secured fifteen more of the same 

 species, all in the same spot. 



They are very local in Nice. 



The females, which preponderated, were very large 

 and brilliant, and generally far lighter in colour than 

 those I have usually seen, especially in the mountains. 

 They were, however, very variable in size. One 

 specimen, a male, whicli I have before me, measures 

 only 1" 1'". Its right h.-w. is imperfectly developed, a 

 not unusual occurrence, where there is a large 

 number of one particular insect. Another individual 

 and a female, from the same place, measures 

 exactly an inch-and-a-half ! 



At this period they were abundant, settling on the 

 flowers of Onobrychis, &c. 



As a rule, the females, especially, swarmed on the 

 flowers of Origanum vulgare (Wild Marjoram), to all 

 appearance laying eggs . 



Origanum is closely related to Thyme, on the latter 

 plant of which, as has before been stated, the larva of 

 Arion feeds. I may here mention that this form of the 

 female might well be considered as a constant variety, 



