1 on 



^'•^^^^ ^'<5RK STATE MUSEUM 



J. ,. bo, ed or treated wit,, hardening agents. TI,e interior 

 of tl,e cvi,nde.. ,s traversed b,- interwoven cords. As many as 19 

 «p.res have been eonnted in one egg mass and since each spire 

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

 or even more." 



In an nndetormined North American species observed by the 

 wr,ter the egg n,a.ss is in the form of a clnmp enveloped in gela- 

 t.ne, wh,ch is moored by means of a cord to a stone or a Ceed 

 a ong the bank of a poo,. The eggs within this clump have no 

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

 An,er,can species lays a string in which the eggs are arranged 

 as shown ,n flg.l5, and stil, anot,,er as shown in fl.. 12 



.lenrr'', ;^" *"' 'r™' "' *"' '™""^^^ "' '"^ group are rather 



prole' 'roTrr ™T ■ * ""'' '"' P»"^^^ *^»™"« -d -"' 

 prolegs (p,.16). m s,ze the mature larvae vary from 4 or 5 mm ' 



to upwards of 25 mm. Many of the largest species are blood r«l 



m color While the smaller ones are yellow, light or dark green 



-own,sl, or pink. The head is sma„, brownish in color, heav ly 



h,t,n,zed, and a little longer than wide. The sclerites of the head 



ns.st Of a dorsal, ventral, and t.-o lateral plates, besides a Zl 



oZlT"r- 7'" '""'' ""^"'^ '^ ^'°"»"'-"<' .bield-shaped, 

 Ptate ,s the labrum, wh,ch hangs fiap-like in front of the mouth 

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



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

 ture; .t ,s attached at its anterior margin, its f,-ee marg,n proje t, 

 ventrad and caudad. Its form varies in the differ:nt gen 

 The lateral plates bear two pairs of rudimentary eyes (prJent 



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

 lateral plates; they consist of a compan.tlvely long basal onl 

 and several shorter terminal ones. The mandibles (pI.S Tl 



five toothed marg,n. They are articulated in such a manner that 

 they move ,n an oblique plane, striking the labium (pI.lB, flg.5) 



n arJn r« " """'''" "' '■"""=' "^ ^^''^^'^^t -»'' *!>« '™nt 

 mn.g,n of the ventral sclerite of the head, the suture separating 



