DEVELOPMENT OF A PODURID. 141 



the embryo shortly before it is hatched ; figure 167, side view of 

 the same, the figures as in Fig. 165; sp, spring; I, labrum. The 

 labrum or upper lip, and the clypeus are large and as distinct as 

 in the embryos of other insects, a fact to which we shall allude 

 again. The large three-jointed spring is now well developed, 

 and the inference is drawn that it represents a pair of true 

 abdominal legs. The embryo when about to hatch throws off 

 the egg-shell and amnion in a few seconds. The larva is per- 

 fectly white and is very active in its movements, running over 

 the damp, inner surface of the bark. It is a little over a hun- 

 dredth of an inch in length, and differs from the adult in being 

 shorter and thicker, with the spring very short and stout. In 

 fact the larva assumes the form of the lower genera of the 

 family, such as Achorutes and Lipura, the adult more closely 

 resembling Degeeria. The larva after its first moult retains 

 its early clumsy form, and is still white. After a second moult 

 it becomes purplish, and much more slender, as in the adult. 

 The eggs are laid and the young hatched apparently within a 

 period of from six to ten days. 



Returning to the stage indicated by figures 166 and 167, I am 

 induced to quote some remarks published in the Memoirs of 

 the Peabody Academy of Science, No. 2, p. 18, which seem to 

 support the view that these insects are offshoots from the Neu- 

 roptera. 



"The front of the head is so entirely different from what it is 

 in the adult, that certain points demand our attention. It is evi- 

 dent that at this period the development of the insect has gone 

 on in all important particulars much as in other insects, espe- 

 cially the Neuropterous Mystacides as described by Zaddach. 

 The head is longer vertically than horizontally, the frontal, or 

 clypeal region is broad, and greater in extent than the epicra- 

 nio-occipital region. The antenna are inserted high up on the 

 head, next the ocelli, falling down over the clypeal region. 

 The clypeus, however, is merged with the epicranium, and the 

 usual suture between them does not appear distinctly in after 

 life, though its place is seen in figure 167 to be indicated by a 

 slight indentation. The labrum is distinctly defined by a well 

 marked suture, and forms a squarish, knob-like protuberance, 

 and in size is quite large compared to the clypeus. From this 

 time begins the process of degradation, when the insect assumes 

 its Thysanurous characters, which consist in an approach to the 



