738 PROCEEDINGS OF THE ACADEMY OF [Oct., 



THE DEVELOPMENT AND STRUCTURE OF THE LARVA OF PARAGORDIUS. 



BY THOMAS H. MONTGOMERY, JR., 

 Professor of Zoology in the University of Texas. 



The embryology of the Gordiacea is a subject full of mystery and 

 interest, notwithstanding the attempts at its solution. It is one 

 fraught with technical difficulties, and one where the obtaining of 

 material is usually a matter of chance. With a peculiar delight then, 

 after many vain attempts to collect the eggs, I found in March and 

 April of the present year numerous adults of both sexes, with egg- 

 strings in abundance, of Paragordius varius (Leidy) in a small stream 

 that passes through the town of Austin, Texas. 



Ovipositing females were brought to the laboratory, and the egg- 

 strings kept for weeks in small jars of water aerated by plants. The 

 full-formed larval stage is reached in from ten to twelve days, and 

 these larvfe live for more than a week longer before they leave the 

 egg-membranes. After leaving the latter they live for only a few 

 days unless they reach their proper host. 



In Texas, as in Pennsylvania, the last host is the large cricket 

 {Acheta abbreviata) ; in this host are found individuals from about one- 

 third the ultimate size to the adult stage. As is well known for all 

 the species of Gordiacea, the adults leave their terminal hosts and come 

 into the water, wdiere the eggs are fertilized and laid. Whether the 

 cricket is the only host of Paragordius varius, or whether there is a pre- 

 ceding one into which the larva first enters, I have not yet been able 

 to determine. Attempts were made to infect crickets with larvae, by 

 crushing the egg-strings containing the latter so as to liberate the larva, 

 and placing drops of water filled with the larvae upon grass fed to the 

 crickets. None of the adult crickets lived longer than a month in 

 confinement; and each one out of about 75 kept under observation 

 was examined in vain at the time of its death for Paragordius larv£e. 

 Crushed egg-strings were placed in water containing Amphipods 

 (Gammarids) ; at the end of two weeks the Amphipods showed numer- 

 ous larvffi encysted in the intestine and musculature, but these larvae 

 underwent no further development. Terrestrial Isopods (Oniscus) 

 found in damp places were placed in contact with water containing 



