OBSKRVATIONS ON THE GENUS CATOCALA. 259 



beini^ quite rudimentary ; the 5th al)doininal has a somewhat 

 swollen appearance. The liead is hirger tlian the body sej^ments. The 

 tul)ereles are generally rather prominent, each bearing a short hair. 

 They consist of dorsal, trapezoidal tubercles, and five laterals on 

 each side. In the second instar t'.iaj are very similar, but the prologs 

 on the 3rd and 4th abdominal segments are developed (though very 

 small), and the hump on the 5th abdominal is slightly developed in all 

 but C. fraxini and C. retecta. In the third instar the larvae tend to be 

 very specialised; C. nupta and C. electa then assume their first 

 brightly-coloured coats, whilst C. sponsa and C. promissa develop the 

 white horseshoe marks, and 0. fraxini and C. retecta assume the 

 adult pale green-grey tint, with fine longitudinal black lines. Tlie 

 humps are now well developed ; even C'. fraxini and C. retecta have 

 the 5th abdominal swollen, and a black horseshoe mark partly on the 

 5th and partly on the 6th abdominals. The tubercles have now become 

 yellow or orange-coloured. ( '. fraxini and C. retecta have a trace of the 

 lateral fringe. The fourth instar is very like the last ; in it, the adult 

 markings of all the species are assumed ; the humps on the 5th abdominals 

 are well developed, but C. fraxini and C. retecta never have them as 

 large as the rest. The lateral fringes are also developed. In the last 

 instar the larvaj are very long and slender in comparison with their 

 length ; the head is bilobcd, with a dark streak on the top of each 

 lobe, which thins out down the side of the face. The first two 

 abdominal segments are elongated to about twice their normal length, 

 the 3rd and 4th to about one-and-a-half. The 3rd, 4th, 5th and 6th 

 abdominal segments are somewhat more swollen than the rest, 

 especially the 5th, which bears a very prominent fleshy hump, situated 

 between the two posterior dorsal tubercles. On the 8th abdominal the 

 posterior dorsal tubercles are much enlarged, and point backwards 

 towards the anus, forming a sort of double hump. The body is flat- 

 tened beneath in C. fraxini and C. retecta to such an extent, that a 

 cross-section would be somewhat of the shape of a capital letter D 

 placed on its flat side, the remainder are somewhat rounder above. 

 The prolegs are spread out very much sideways, especially those on the 

 5th, 6th, and last abdominals, giving the larva a very sprawling 

 appearance, and enabling it to press its flat underside against the twigs 

 of the food-plant, and thus escape detection. The lateral fringe, 

 which consists of a series of short stout filaments along each side, also 

 aids in this deception, as wlien the larva is resting on a twig, the 

 fringe is pressed against it, and no dividing line between the larva and 

 the twig being apparent, the twig merely appears somewhat swollen. The 

 legs are generally the same colour as the head. The larvas are always 

 pale coloured beneath, with large dark spots in the centre of most of the 

 segments. These are generally of a deep crimson or brown colom*, and 

 are flushed round the edges with pink, but in C. elocata the crimson 

 flush is extended over nearly the whole of the underside ; in C. fraxini, 

 on the other hand, there is no flush and the spots are very small. These 

 curious spots are no doubt used as a prt itection to terrify enemies, for 

 when disturbed the larviu turn upside down, and twist themselves into 

 circles sideways very violently. These curious s})ots are by no means con- 

 fined to Catocala, as various tree-feeding Noctuid and Geometrid larva) 

 possess such sj)ots, notably, Miselia oxyacanthae and Metrocampa mar- 

 garitaria. The tubercles, with the exception of the posterior dorsals, 



