March, :9i7-] WiLLIAMS : NoRTH AMERICAN LaMPYRID^. 25 



tened against an object, later it grows and rounds up somewhat and 

 develops a firm and brittle shell. Long ago Newport (On the Nat- 

 ural History of the Glowworm, 1857) noticed the growth of the laid 

 eggs and found them to be effulgent. Seaman (1891) says: "The 

 eggs of the Lampyrid?e and Pyrophori may be dried to their utmost 

 without losing their photogenic property." Dubois (1898) adds that 

 the eggs of Pyropho'riis noctiluca, the large luminous Elaterid of the 

 neotropical regions, shine when unfertilized, and even while in the 

 ovarian tubes. He states that they have great affinity for moisture 

 and will even glow when placed near a green blade of grass. Mr. H. 

 S. Barber writes me (June, 1914) concerning Phengodcs laticollis 

 that "luminosity develops in the egg before hatching." The eggs of 

 Photuris pcnnsylvanica certainly glow when deposited, and till they 

 are from two to four days old, and therefore probably throughout 

 their life, but the effulgence is often so faint that it can be perceived 

 only by careful and protracted scrutiny in total darkness. In July, 

 1914, I squeezed several eggs out of the ovary of a living Photuris, 

 and placing these in water, carefully examined them in the darkness. 

 But they were not found to shine and so they were crushed and 

 placed in hydrogen peroxide, when at least one e:g,g emitted a faint 

 luminescence. 



In the laboratory eggs of Photuris hatched in about fifteen to 

 eighteen days, into peculiar, very active, somewhat turtle-shaped 

 larvse about 2.20 mm. long. At first whitish, except for the blackish 

 eyes and pale yellowish-brown of the feet, mouth-parts and antennae, 

 the larva darkens in the course of a day or two and becomes slaty 

 gray with the head largely brownish. The length of the body is 

 now about 2.50 mm., including the extended head 2.70 mm., its width 

 at the third segment i mm. The head is depressed cylindrical, a little 

 more than twice as long as wide and hardly one third the width of the 

 prothorax. The eyes are simple and rather large, the antennae short, 

 tapering and three-jointed, the first joint is membranous and the third 

 bears a cylindrical sense-organ distally and a lobed process before the 

 end. The jaws are stout, arcuate and notched before the tip. The 

 body is oblong oval, tapering more caudally, with the sides above de- 

 pressed, forming a rather prominent median ridge ; the prothorax is 

 about as long as the meso- and metathorax combined, the latter two 

 are each longer than any of the abdominal segments with the possible 



