THE PHYLOGENY OF THE LEPIDOPTEROUS PUPA. 95 



A typical pupa-obtecta may be found in most Noctuids, e.g., Xylop- 

 hana monoglypha. It is smooth and polished from end to end, has no 

 spines or roughness, except the anal spines forming the cremaster (not 

 a good name here, as they hold in no silk), and corresponding to the 

 suranal plate of the larva, and some pitting on the anterior margin 

 of the 4th, 5th, 6th, and 7th abdominal segments. The anterior 

 portion of the pupa is a solid mass down to the 4th abdominal 

 segment inclusive, and on this are seen marked out the eyes, proboscis 

 (maxilla), two pairs of legs, antennas, and wings, whilst a portion of 

 the labial palpi is seen between the two portions of the proboscis, and 

 between them and the first legs a portion of the first femur, but these 

 are smoothed down to one cylindrical surface including them all. It 

 is quite hopeless to attempt to separate these parts, and when the 

 moth emerges we have difficulty in finding the delicate membranes 

 within that represents the pupal skin (two layers) of these parts (legs, 

 wings, &c.) where they lay against each other. Dorsally, all the 

 segments are represented except the head ; the 5th and 6th abdominal 

 segments are free ; the 7th-10th are fused in one mass ; there is no 

 dorsal head-plate, no maxillary palpus, &c. The "waist," a narrowing 

 of the 3rd thoracic and the 1st and 2nd abdominal segments, is not 

 noted till looked for, and is very slight. 



It is characteristic of the pupas-obtectae to have a great general 

 resemblance to each other, even when, almost certainly, they belong 

 to families derived from different sources. The Geometrids are not 

 related to the Noctuids, yet it would be difficult, in many cases, to 

 point out in a Geometrid, any definite character that distinguishes it 

 from a Noctuid, pupa. The Deltoid pupa has a very Geometrid aspect. 

 The Geometrid, pupas differ, as a whole, in being less uniform than 

 those of the Noctuids, i.e., there is a considerable range from lower to 

 higher forms within the family. Some few Geometrids possess pupae 

 with a fairly developed dorsal head-piece, tending to carry the eye- 

 pieces, a feature not observed in any other pupse-obtectae, except that 

 of the Hesperiids. The mass of them, however, are very close to the 

 Noctuids in appearance, as already stated. They are usually more 

 slender, and taper more generally and regularly to the anal extremity, 

 but there are many exceptions. This wide difference of pupal structure 

 is hardly met Avith in any other family. It is paralleled by the similar 

 variation in the Geometrid eggs. The flat egg that characterises the 

 family gives place in a few Acidaliids and others to an upright egg, 

 ribbed like that of a Noctuid or Pierid. This uniformity of the pupas- 

 obtectre seems to be referable to the fact that it represents the most 

 desirable structure to meet the requirements of emergence of the imago 

 leaving the pupa case behind. 



Amongst the pupae-obtectaa, besides those that have already been 

 referred to, the Cymatophorids, the Lasiocampids, and some Notodonts, 

 carry a dorsal bead-piece. Amongst our British Cymatophorids, the 

 form of this dorsal head-piece is characteristic in each species, and 

 would serve for its identification. There is usually little difficulty in 

 distinguishing a Notodont from a Lasiocampid pupa. The Notodont 

 has not always the head-piece, the Lasiocampid has. The Lasiocampid 

 usually has a, dull surface, and any cremaster consists usually of 

 numerous hairs like a brush ; "whilst the Notodont pupa is usually 

 polished and smooth, and the cremaster is usually of a solid, spinous 



