NOTES ON THE EARWIG. 29 



November 8th, 1 pairs seen in 2nd jar. 

 „ 15th, 1 ,, „ 1st „ 



16th, 1 „ „ 1st „ 

 20th, 1 „ „ 1st „ 

 These latter records are no doubt faulty from a much less close 

 scrutiny being kept on the jars. 



Whatever function the forceps may have in courtship, they appear 

 to have no prehensile or other office in pairing. 



February 2nd, 1917. — A nest was made in jar I., and eggs were 

 laid on or before December 12th. These hatched on January 9th to 

 11th, and the young larvae are now apparently thriving. Other nests 

 have been made since and eggs laid. The jars are in a warm room. 



Explanation of Plates. 

 Plate I. 



Fig. 1. — Earwig in first instar x 8. The antennal joints are 8 in number. The 

 cerci are very straight and do not taper. The second joint of the tarsus 

 ahnost persuades one that it is ankylosed to the first. The tarsi of the 

 second and third legs have joints of nearly uniform thickness through- 

 out, and the articulation of the 2nd and 3rd is over the full thickness 

 of the joints, just as the 1st and 2nd is. But the tarsus of the 1st leg 

 has the 2ad joint a little produced ventrally, and the 3rd joint has a 

 narrow articulation to it towards its dorsal margin. This is the struc- 

 ture of the tarsus of all the legs in all the following instars, i.e., articu- 

 lation 1st to 2nd full width of joints, but 3rd joint tapered proximately 

 and with a small articulation to dorsal margin of 2nd. 



The specimens from which these photographs are taken are not 

 too successfully mounted for that purpose, and those of the 2nd instar 

 were decidedly not good enough, so that we have in 



Fig. 2. — Third instar, x 6, the antennse have ten joints, and all the tarsi are as 

 referred to above. The cerci are still rather straight and of uniform 

 thickness. 



Fig. 3. — Fourth instar, x 5. Antennal joints 11, in this specimen the right 

 antenna has only 10, the last joint appears to be a normal last one, the 

 third joint is rather longer than on the other side, showing a probable 

 intention to add another joint. The cerci show something of the adult 

 curving and tapering. 



Plate II. 



Fig. 4. — Fifth instar, x 4. Antennal joints 11. 



Fig. 5. — Sixth instar, x 4. Antennal joints 12. The second and third thoracic seg- 

 ments show the extension to accommodate the developing wings. At 

 this (pupal ? or penultimate) stage, the cerci seem to be about the same 

 in both sexes. 



Fig. 6. — Seventh (imaginal) instar, x 4. Elytra and wings shortened or removed. 

 Antennal joints 14. This specimen is chosen notwithstanding its 

 defects as showing cerci suggesting hermaphroditism, the one that looks 

 like a'femaleis, from its appearance, with but little doubt a regenerated 

 one, that wanted another instar to become normal, in other words, the 

 loss of the appendage occurred during an iustar at least one too late for 

 complete regeneration to occur by the time the imaginal stage was 

 reached. 



Plate III. 



Camera sketches to illustrate the appearance of the oval rings 

 found in all stages and in the cast skins. It is remarkable that they 

 were never lost in preparing and mounting specimens, either of the 

 insects themselves or their cast skins. But the variety in their disposi- 

 tion may be due to this cause, in no two specimens are they placed 

 exactly alike. In one specimen only are they absent, it shows no 

 definite damage in mounting by which they might have escaped. Fig. 



