OP ARTS AND SCIENCES. 87 



, 3. Appearance of a yellowish lateral oblique stripe connecting the 

 lateral tubercles of the lower and upper row, in Stage III. 

 4. Appearance of the pale purplish edging of the suraual plate and 



anal legs, in Stage III. 

 0. Appearance in Stage IV. of the pearly spot on the outside of the 

 dorsal tubercles. 

 The generic characters are mostly assumed in Stage III. 



The Life History of Actias luna (Linn.). 



The esrofs were received from Mr. James Angus. 



JEgg. — Oval-cylindrical, somewhat flattened. The shell is thick and 

 tough, dark brown externally, but in places the brown is worn off, 

 leaving a dull, sordid chalky whitish surface ; the inside of the shell 

 slightly bluish gray. The surface of the shell is seen under a ToUes 

 triplet to be rough and finely granulated, and under a half-inch objec- 

 tive, the surface is seen to be closely granulated, the pits between the 

 granulations being often confluent ; rarely the raised bosses appear to 

 be polygonal. Length 2.1 mm., breadth 1.8 mm. 



Larva, Stage I. — Length 6-8 mm. Some were observed hatching 

 out between 11 and 1 o'clock p.m., June 15. Before entirely break- 

 ing: out of the egs-shell the tubercles on the anterior segments become 



"o 



erect, and the hairs radiate from them, but behind along the 3d thoracic 

 and abdominal segments the tubercles were seen to be soft, and flat- 

 tened or appressed to the body, and adhering in flaccid bundles. In 

 P. cecropia, on the other hand, all the tubercles and bristles are flabby 

 for perhaps half an hour after the creature frees itself from the egg. 



One was seen to emerge at 1.15 p.m., and by 1.25 p.m. all the 

 tubercles had become filled out and erect, with stiff radiating bristles.* 

 On hatching, the body is entirely green, except the bands on the head. 

 Some larvae on hatching are (a) entirely yellowish green, while the 

 dorsal hairs are darkish, and the head is twice banded. Others 

 (b) have a very broad blackish lateral band, enclosing one lateral row 

 of greenish tubercles, the band ending on the 8th abdominal segment, 

 and nearly meeting above. The prothoracic segment is dark on the 

 hinder edge, and the 2d and 3d thoracic and 1st abdominal segments 

 are entirely dark above. 



* It is evident that before and at the point of hatching the setae or bristles 

 are filled with blood, which distends them. While thus distended, the fluid may- 

 ooze out of the ends, and thus they may be called glandular hairs. In those 

 which are full and bulbous at the end, the fluid may be retained through Stage 

 I., and in rare cases through the second or even the third stage. 



