THE VICTORIAN NATURALIST. 101 



some stalked, others moving, very deliberately indeed, are in the 

 field, as well as pretty Desmids, Closterium, Pediastrum, or 

 others. But none of these, however beautiful or interesting, 

 concern us now. The more fascinating animal life is our object ; 

 and this is most abundantly represented by the Rotifers, or 

 Wheel Animalcules. These almost inevitably attract our notice 

 first, owing to their liveliness, immense variety of curious forms, 

 and the elaborate structure disclosed by their very transparent 

 bodies. Nor are the charms of colour wholly wanting. No 

 small recommendation, too, is the fact that these interesting 

 creatures can be effectually studied with quite modest means. 

 An unpretentious little microscope, equipped with only two 

 lenses, say an inch and a quarter inch (but both good), will 

 suffice to carry us a long way in this pursuit. We had better, 

 perhaps, add a condenser, lest we appear retrograde and bring 

 criticism on our heads. 



Our friend Mr. Shephard, about two years ago, described the 

 structure and classification of the Rotifera. But it may be advis- 

 able to advert briefly to the former ; the latter will appear, to 

 some extent, as we go on. 



First, then, we notice the head, with its highly characteristic 

 appendages, the ciliary wreaths ; and, in some cases, setae, or 

 stiff bristle-like attachments. These vary greatly in the different 

 species, in many of which the cilia, by rapid successive move- 

 ments, produce the well-known and no less wonderful illusion of 

 revolving wheels — an illusion from which we cannot escape, 

 though we look at it for the hundredth time. On the under side 

 of the head is a somewhat V-shaped opening, the buccal orifice, 

 which serves as a mouth, and leads by a funnel-like tube, guarded 

 at the bottom by two tiny lips, to the mastax. This mastax 

 is a loose muscular bag enclosing the two trophi. These 

 trophi, or internal jaws, form a very special and conspicuous 

 feature in Rotifers. They are complex in structure, consist- 

 ing of three main portions, two called mallei, or hammers, 

 and the third, between them, called the incus, or anvil. 

 These elements, also, are subject to great modification. 

 The function of the trophi is to grind up the food, and this 

 operation can easily be seen constantly going on. From the 

 mastax, a short tubular oesophagus leads to a sack-like stomach, 

 followed by intestine and rectum. Cilia line the whole of this 

 alimentary canal. Three sets of glands are distinguished. The 

 so-called salivary glands are attached to the front of the mastax; 

 the gastric glands to the front of the stomach ; two foot glands 

 secrete a sticky substance, which assists the Rotifer to adhere 

 wherever it desires. A ganglion, or brain, with threads running 

 to the eyes and antenme, makes up the nervous system. The 

 latter are the Rotifer's sense organs. The eyes are small spots, 



