180 NEW YORK STATE MUSEUM 



mass is boiled or treated with hardening agents. The interior 

 of the cylinder is traversed by interwoven cords. As many as 19 

 spires have been counted in one egg mass and since each spire 

 commonly contains abont 45 eggs, the total may amount to 850 

 or even more." 



In an undetermined North American species observed by the 

 writer, the egg mass is in the form of a clump enveloped in gela- 

 tine, which is moored by means of a cord to a stone or a weed 

 along the bank of a pool. The eggs within this clump have no 

 definite arrangement but lie at random (fig.lO). Another North 

 American species lays a string in which the eggs are arranged 

 as shown in iig.15, and still another as shown in fig.l2. 



Larva. All the larvae of the members of this group are rather 

 slender, have a rather short head, and possess thoracic and anal 

 prolegs (pl.l6). In size the mature larvae vary from 4 or 5 mm^ 

 to upwards of 25 mm. Many of the largest species are blood red 

 in color, while the smaller ones are yellow, light or dark green,^ 

 broAvnish, or pink. The head is small, brownish in color, heavily 

 chitinized, and a little longer than wide. The sclerites of the head 

 consist of a dorsal, ventral, and two lateral plates, besides a num- 

 ber of smaller ones. The dorsal sclerite is elongate shield-shaped, 

 often with a few setae. Attached to the front margin of this 

 plate is the labrum, Avhich hangs flap-like in front of the mouth 

 and may be bent backward ; and on the under surface are several 

 pairs of setae, usually pectinate. Attached to the ventral surface 

 of the labrum is the epipharynx. This is a rather complex struc- 

 ture ; it is attached at its anterior margin, its free margin projects 

 ventrad and caudad. Its form varies in the different genera. 

 The lateral plates bear two pairs of rudimentary eyes (pigment 

 spots) as well as the antennae and the jaws. The antennae (pl.l6» 

 fig.5, and pl.22, fig.la) are situated on the anterior end of the 

 lateral plates; they consist of a comparatively long basal joint 

 and several shorter terminal ones. The mandibles (pl.22, fig.l, 

 md) situated ventrad of the antennae are stout and have a four or 

 five toothed margin. They are articulated in such a manner that 

 they move in an oblique plane, striking the labium (pi. 16, fig.5). 

 The labium is attached or rather is coalescent with the front 

 margin of the ventral sclerite of the head, the suture separating 



