790 



MICROSCOPIC FORMS OF ANIMAL LIFE 



antenna has a similar bundle and lies sheathed in a tube (fig. GO")) 

 which has its base just above the nervous ganglion, and passes 

 thence between the two central anterior spines of the lorica. It is 

 furnished with a muscle, by means of which the bunch of seta> at 

 the free extremity can, by imagination, be drawn within the tube. 



The ovary is large and its germs are conspicuous. The animal is 

 oviparous and the huge egg is easily discharged through the oviduct 

 and cloaca owing to the very fluid condition of its contents. It is 

 retained by a thread till hatched at the bottom of the lorica. There 

 are three kinds of eggs : the common soft-shelled eggs, which arc 

 large, oval, and produce females; similar soft eggs, which an- 

 smaller, more spherical, and produce males ; and ephippial eggs (fig. 

 603), with thick cellular coverings, often ornamented with spines. 

 These latter can be dried completely without losing their vitality, 

 and so, lying buried in the mud of dried-up ponds, preserve the 

 species for next yaar. 



FIG. 603. 

 Ephippial egg. 



FIG. 604. Male : e, eye ; Zc, longi- 

 tudinal canals ; i'f, vibratile tag; 

 cv, contractile vesicle ; ss, sperm- 

 sac ; 2>, penis ; /, foot ; fg, foot- 

 gland. 



The male (fig. 604) is but a third of the length of the female, 

 and is unlike it in shape. It has a cylindrical trunk, small foot, and 

 flat round head, surrounded by a simple ring of long cilia. It has 

 no lorica nor any alimentary tract of any kind, but it has a 

 nervous system similar to that of the female, a red eye, and anteniue. 

 Its excretory and muscular systems are also of the female pattern. 

 The only other internal organ is a large sperm-sac (ss) ending at its 

 lower extremity in a protrusile, ciliated, hollow penis (p), whose 

 outlet holds the position of the anus in the female ; that is, on the 

 dorsal surface, at the base of the foot. 



The Rotifera have been divided by Dr. Hudson anil Mr. P. H. Gossc ! 

 into four orders, according to their powers of locomotion. These a n : 

 1. RHIZOTA (the rooted). Fixed when adult. 



1 The Rotifera, or Wheel-animalcules. Longmans, 1889. It should be added 

 that Dr. Plate, in 1890 (Zeitschr. f. wiss. Zool. xlxi.), has suggested a division 

 according to the paired or unpaired character of the gonads. 



