RECREATIONS WITH THE MICROSCOPE 



379 



that the algae becomes a mass of wi rms. 

 It is thought that these worms are in 

 part responsible for the disappearance of 

 the large masses of algae and other low- 

 plants in the fall. < hie of the commonest 



( OMMON WATER-MITE. 

 With palpus (at right). 



of these worms is Stylaria which is easily 

 known by its peculiar proboscis at the 

 front end of the body. 



< >f all the species of aquatic animals 

 that are found in algae rone are more 

 numerous or of greater value economi- 

 cally than the minute larvae of certain 



curious trunk- 

 like extensions 

 of ol1gochaete 

 aquatic earth- 

 worms (stylaria) 



flies called midges (Chironomus ) . These 

 are jointed, worm-like creatures, with 

 tube-like gills attached to the posterior 

 part of the body. They are herbivorous 

 animals eating great quantities of the 

 algae and furnishing in turn food mater- 

 ial for a number of fish. These larvae 



mass of vegetation. These are Planaria 

 or Turbellarian worms. They are up- 

 wards of half an inch in length, spotted 

 with purplish or brownish, and the head 

 is provided with an ear-like expansion on 

 each] side. These animals are predatory 

 and feed usually at night. Looking much 

 like the planarians hut much larger an 1 

 made up of many segments or rings are 

 the leeches (Hirudinea) a few small 

 species of which are usually found in 

 algae. These are also predatory animals, 

 hunting and consuming the smaller 

 herbiborous creatures living in the algal 

 mass. Some leeches, as Glossiphonia, 

 eat such a large number of snails that 

 they are known as snail leeches. 



Mollusca or snails also inhabit our 

 handful of algae, often in as great abun- 

 dance as the worms and fly larvae. Most 

 conspicuous among these are the little 

 spiral snails called Amnico'la, specimens 

 of which vary from to to five mm. in 

 length. The small whell-snail's, PJanor- 

 bis, also abound, and may he represented 

 by several species, one of which. Plan- 

 orbis hirsutus, may be known by the 

 hairy epidermis covering the shell. Other 

 soecies of snails may be present, Lynuura, 

 Physa, Ancylus, Valvata, and perhaps, a 

 few of the small finger-nail shells. Pisi- 

 diuiu. Many of the snails in algae are 

 young or immature and later in life mi- 

 grate to the rocky chores and live dur- 

 ing maturity. Such an example is found 

 in Lymihca catascopmm which abounds 

 in algae when from two to six mm. long 

 but is found onlv on rocky or sandy 

 shores in some lakes when adult. 



And so. in our examination of a hand- 

 ful of algae, we find indeed a miniature 

 world of animal life, the careful studv 

 of which might occupy our time for many 

 weeks. Onlv a verv few of the many 



A BLOOD-WORM. 



Chironomous larva; of astonishing 

 antics. 



construct a case of the fine material at 

 the bottom of the water by cementing 

 together "'fains of silt or sand with the 

 silk-like secretion of their salivary 

 glands. Some of these larvae are red in 

 color and are known as "blood worms." 

 As we carefully examine the algae in 

 our study we may chance to observe cer- 

 tain flat objects slowly crawling over the 



forms of animals living in an algal com- 

 munity have been mentioned. In addi- 

 tion we would find the curious little 

 ostracods in their bivalve shell looking 

 quite like a small mussel ; many insect 

 larvae, such as May-flies, the caddis- 

 flies, the bugs, hunters in search of their 

 prey competing with the larvae of beet- 

 les ; and also the infinite number of fla- 



