346 OK SOMK TRRMATODK PARASITES OF AUSTRALIAN* FROOS, 



The body is very similar in shape to P. JrfT/cinrfi, ]n\t miu-h 

 smaller; only about half the size. While the spines of P. sohts 

 are much smaller, their arrangement is very similar to tliat found 

 in P.freycineti* 



Literature referred to. — 38, 48, 60, 66, 91. 



Section v. 

 Egg-formation and the function of Lniirers (Javnl. 



While studying living specimens of Dolichosacrns frijphenis 

 mounted in normal saline solution, I noticed the process of egg- 

 formation going on, and, under the high power, was able to follow 

 out many of the details. The ripe ova leave the ovary generally 

 (and apparently normally) one at a time. Lying foi- a short time 

 at the entrance of the oviduct, it is suddenly expelled from the 

 ovary, entering the oviduct with a little gush, and almost imme- 

 diately finds itself in the fertilization-space, where it is at <mce 

 vigorously attacked by a large number of spermatozoa which com- 

 pletely surround it. This fertilization-space, which, as already 

 described(p.312) is of great size, is generally filled with very 

 lively spermatozoa, and fertilization takes place in that part 

 opposite to its opening into the oviduct(Fig.5). For a few 

 seconds, tliere is a very energetic turmoil, when, suddenly (one 

 apparently having entered the ovum, though this could not be 

 seen owing to the dense mass of sperms surrounding it) the 

 spermatozoa leave the ovum, and at once enter Laurer's canal, 

 down which they move with extraordinary energy. The Laurer's 

 canal in this species is a ver}' long one, pursuing a tortuous 

 course right down to the level of the anterior testis, in which 

 region it opens on the dorsal surface. The flight of the spei'ms 

 seems to be influenced by the pressure of the surrounding tissues 

 on the Laurer s canal, for here and there their onward rush is 

 checked, and a wave of backward movement occurs for a moment; 

 but they soon move onward again, and finally rush out through 

 the opening of the canal into the surrounding salt solution. 



* Later, twelve addiiioiial siieciiiieiia were found ami placed at my dis- 

 posal by Mr. E. A. J>iiggsi, Assiataiit Zoologist to the Australian Museum. 



