22 Proceedings of the Royal Society of Victoria. 



of the cuticle is longitudinally striated. These striations were 

 seen in the cut edges of the cuticle in sections to be actual 

 corrugations, and their distance apart I estimated at -0005 mm. 



External Feahires of Young Female (Fig. 4). These are found 

 swimming freely and are much smaller than the adult, being 

 only -So mm. in length. The body is a very gradually tapering 

 cone, widest at the head and ending bluntly. The eyes are 

 more conspicuous than in the adult. At the extremity of the 

 foot there is a ciliated cup (c.c.) in communication with two large 

 glands, of which I shall have to speak later. 



Male. — Having a large number of colonies, a little watching 

 soon discovered the male. Numerous specimens were seen 

 hovering around the colonies and occasionally plunging between 

 the closely packed females. They were very active and of small 

 size, only -17 mm. in length, or -j^-th of the length of an adult 

 female. In general outline the male (Fig. 4^) resembles pub- 

 lished figures of Z. socialis. A ciliated pit (Fig. 4(7, c.p.) is 

 placed on the ventral surface near the termination of the foot. 

 The conical front has a strong tuft of setpe at its apex seated 

 upon a nerve cell, from which a thread runs backwards to what 

 appears a large nerve mass. The whole of the conical front is 

 ciliated, and there is a ring of strong cilia at the base of the 

 cone which is continued for a short distance ventrally, and is 

 suggestive of a buccal orifice. There are two red eyes, and 

 about \ of the length of the animal from the front is placed a 

 conspicuous dorsal antenna connected with the nerve mass. 

 Mastax and alimentary system are absent, the latter being repre- 

 sented by a cord running down the centre with a thickened 

 portion about the middle. The sperm sac (Fig. 4, s.s.) is placed 

 near the retractile penis and varies much in size, one specimen 

 having the whole body cavity occupied by it. 



Internal Anatomy of Female. Methods. — Mr. Rousselet's A^alu- 

 able method of killing^ answers admirably with this form, and 

 whole colonies with almost every individual fully extended could 

 be obtained. It was necessary to follow up the first dose of 

 cocaine mixture quickly with strongei- doses and narcotize 

 rapidly, as if the process was too prolonged the animals left the 



I Jour. Queck. Micro. Club, \ol. v., ser. 11, p. 5-13, No. 30, March, 1S95. 



