186 THK kntosiologist's record. 



as observation could be made. The period of closure became lonp;er 

 and longer. The movements of the valves were synchronous with the 

 vermicular movements, but not with the pulsations of the dorsal 

 vessel. During actual moulting the valves were quite closed. As 

 well as the chitinous dark margin to first spiracle, the abdominal 

 flanges and the anal spine, there was also a slight chitinous tinting of the 

 dorsum of the mesothorax. The lateral stripes of the larva were again 

 very bright, and there are reddish spots (non-chitinous) at the sites of 

 the prolegs. The 8th abdominal spiracle yields as strong a tracheal lining 

 as the others, yet seems to be quite closed and obsolete, as soon as this 

 is withdrawn. The spiracles of the Gth and 7th abdominal segments 

 are closed in about 15 minutes, those anterior rather later, that of 2nd 

 abdominal segment in about 20 minutes. 



Smeriuthns oceUatns. — At the moult, the larval stripes are visible 

 in dark green, as well as the sites of prolegs. The lips and the anal 

 spine of the 1st spiracle are chitinous. The tube lietweeu the 

 ] st and 2nd thoracic segments leading to the 1st spiracle is uunsally 

 oi)en, and allows the spiracle to be seen at bottom, light being freely 

 afforded through the translucent gxeen tissues. The other dark 

 chitinous parts are the posterior border of the 7th abdominal, and 

 pale Ijands on the dorsum of the 3rd thoracic, and the 1st, 2nd and 

 3rd abdominal, segments, also many of the small cutaneous pits. In 

 another specimen, the stripes and prolegs are a vivid blue, as well as 

 the tips of the mandibles, and four spots at the base of the labrum. 

 In this species the spiracles are closed from the moult, and the move- 

 ments of the valves are not visible. 



Pygacra hucephala. — The larva of this species pupates at from 

 six to "ten days after going down. When the skin has passed so far 

 backwards that the skin of the 11th segment of the larva is at the 

 anal extremity of the pupa, or rather, when the pupa occupies the 1 

 front segments only of the larval skin, the latter splits down 

 each side, just above the ventral prolegs, a short slit in each seg- 

 ment, but usually continues over at least two segments. It is not 

 very evident in what way this advances the moulting, for immediately 

 after the skin splits in the normal dorsal situation, followed l)y tiie 

 division of the larval head into the two lateral and clypeal portions, 

 a tracheal tul^e is drawn out of the meso-metathoracic incision. The 

 1st s]iiracle is so deeply i)laced between the pro- and meso-thorax at 

 the earliest moment, that it is uncovered l)y the receding skin as to be 

 seen with difficulty. The margins of this spiracle at the surface are 

 not a])])arently tinted or hardened. The coloured portions, besides 

 minute hair-points, are the anal s])ines and the dorsal margins of the 

 incision between the 9th and ] 0th abdominal segments, which have 

 curious opposed deutated borders. There is also a trace of colour at 

 the sites of the ventral prolegs. The wing- and apjiendage-cascs are 

 very short, and take about twenty minutes to pass from the margin 

 of the 3rd abdominal segment to their permanent position at the 

 margin of the 4th, but it takes some hours for the solid portion of the 

 ])uiia (head to 4th alKlomiual segment) to grow fi'om a of the total 

 length to f of that of the mature pu])a ; this occurs not only by its 

 own increase in length, Ijut by the shrinking of the last six abdominal 

 segments. The total length of the pu])a is remarkably constant tlu'ougli- 

 out all these changes. The abdominal spiracles on the 2nd, 3rd, 



