188 NYMPHALIDJS. 



Middle and Posterior Legs with the femora slightly longer than the tibiae ; the latter and the tarsus 

 of about equal length. Femora stout, Tibia? nearly cylindric, spiny on each side within ; the 

 spurs long. Tarsi spiny laterally and, except the fifth joint, below ; the spines of the lower 

 surface tending towards an arrangement in a double series. First joint three fourths the length 

 of the rest combined ; second and third nearly equal ; fourth very short ; fifth longer than the 

 second. Claws much curved, grooved below. Paronychia long ; the outer lacinia very slender, 

 pointed, as long as the claw ; inner obtuse, much shorter than the outer. Pnlvillus jointed, 

 nearly as long as the claw. 

 Abdomen moderately stout, about three fourths the length of the inner margin of the wing. 



Lar va spiny ; the head with two spines longer than those of the body ; the prothoracic 



segment unarmed. 

 Pupa angular, tuberculate ; the head bifid. 



This genus may be at once distinguished from the preceding by its hairy eyes, and from the following genera by the 

 position of the subcostal nervules. 



As yet it contains only one species, remarkable for the variations in the colours of the upper surface of its wings, 

 which have caused it to be divided into three nominal species. The typical specimens, which are the P. Prorsa of the 

 Systema Naturce, have the wings, above, fuscous black, with a transverse series of white spots on the disc, and a 

 subinarginal, slender, undulated, brown line. These are common throughout central Europe in the months of July and 

 August. The most aberrant specimens are the P. Levana of Linne. These have the upper surface of the wings 

 fuscous at the base, reticulated with yellowish lines; thence to the outer margin fulvous, spotted with black; and 

 marked with three large yellowish spots near the anterior, and two small white ones near the outer, margin. This 

 variety appears only in the spring, and is less common than the typical one. Intermediate between these is a much 

 rarer variety, sometimes found in the autumn months, and known by the name of Porima. The under surface of the 

 wings in these varieties is not strikingly different in its markings, though offering some differences bearing relation to 

 the colouring of the upper surface. It is of a more or less ferruginous brown, with the nervures, nervules, many 

 transverse lines, a broad transverse band, and some submarginal spots, of a yellowish white; in addition to which 

 marking?, the posterior wings have a submarginal series of pale blue spots. 



These varieties evidently depend on the season of the year at which the perfect insect makes its appearance. Their 

 exact history does not appear to be completely understood, but what is known respecting them is highly interesting in a 

 physiological point of view, as tending to throw light on the effect of temperature in modifying the colours of insects. 

 The insect not occurring in Great Britain, it is to our Continental brethren that we are indebted for observations on its 

 history. 



The pupa; from a number of caterpillars reared in June, and all from the eggs of the same female, were divided into three 

 portions, one of which, being left under ordinary circumstances, produced the perfect insect in the course of the next 

 month. These were all Prorsa. Another portion, placed in a cellar until the following spring, produced only Levana. 

 The third portion, retained at a low temperature until the following July, produced Prorsa and some specimens of 

 Porima. From this statement, perhaps not quite exact, Duponchel seems to conclude that the eggs of Prorsa hatch in 

 August or September ; that the larva? from these become pupa? the same autumn, which pupa?, in the spring, produce 

 Levana ; that from the eggs of this brood of Levana are produced larva? destined to become Prorsa in the following 

 July ; from which, again, arises a brood of Levana; and the fulvous colour of Levana is caused by exposure of the pupa? 

 to the cold of winter. In support of this conclusion, which appears somewhat hasty, lie quotes in his supplement the 

 observations of M. Geyer, published in Treitschke's tenth volume. " On the 29th of July," says that careful observer, 

 " I found at Altmuthal, near Augsburg, many Prorsa flying near the road sides ; I observed them carefully, and saw 

 that there was not one Levana with them. The idea that these butterflies might have deposited their eggs on the large 

 nettles growing hard by induced me to examine these plants. I soon found on the under side of a leaf five little rows 

 of eggs, looking like the broken links of a watch chain. Each little series consisted of about eighteen or twenty eggs. 



