by William Swainson, Zoological Illustrations Series II… (1829)
“ Cassius is one of the most common species of Brazil, where we found it frequenting similar situations, and possessing the same habits, as the ordinary Blues of England. The analysis bestowed upon this group, convinces us that Pithecops, H. is but a section of this sub-genus. The upper figure represents the male, the lower the female: both are enlarged. The connecting species between Polyommatus and Lycæna are Helle, Hub. ”
