14 6 ILLINOIS ACADEMY OF SCIENCE 



and it was first in California that we find the word quarantine 

 as applied to strictly horticultural material. Express ship- 

 ments are as vigilantly inspected as those of freight and 

 steamer. In spite of the strict quarantine laws and the effi- 

 cient service, there still exists an open door by which injurious 

 insects may enter and that is through the mail. This is es- 

 pecially true since the establishment of the parcel post and this 

 door can only be closed by action on the part of congress, 

 whereby the present law requiring the immediate delivery of 

 mail will be abolished and making it mandatory that all pack- 

 ages of fruit and nursery stock be sent to two or three desig- 

 nated post offices for inspection and if found free of injurious 

 insects to be then forwarded to the purchasers. It is toward 

 obtaining such a law that the government is now working. 



THE LABIUM OF THE NYMPHS OF ZYGOPTERA 



PHILIP GARMAN, UNIVERSITY OF ILLINOIS 



Several forms of labia occur in the Zygoptera, differing 

 mainly as regards shape of mentum, submentum and lateral 

 arms. There are also variations in the number of setae pos- 

 sessed by the different parts. 



The labium can be homologized throughout with that of 

 other insects. Palpi, ligula, mentum and submentum are pres- 

 ent. 



The use of the labium for capturing prey has led to rather 

 extensive muscular development within. Two pairs of mental 

 muscles serve to operate the organ to open and close the 

 lateral arm. Two pairs of submental muscles, together with a 

 pair of oblique basal muscles, open and close, extend and re- 

 tract the piece as a whole. The presence of a median un- 

 paired chitinous "rod" or ligament aids in this last 

 operation, and is of interest because it occurs only in the 

 Order Odonata . Caudad it is attached to the dorsal, ental sur- 

 face of the submentum not far behind the articulation of that 

 portion with the head capsule. Cephalad it is fastened to the 

 cuticle immediately behind the hypopharynx. 



