1 62 



SECRETS OF EARTH AND SEA 



w.a 



soon after he had discovered it, I could not believe 



my eyes, and thought I must 

 be dreaming. It is very 

 like the young form of 

 Crustaceans known as a 

 " Nauplius " (see tail-piece to 

 the present chapter) in having 

 (what no other wheel animal- 

 cule has) great hollow paired 

 limbs moved by striated mus- 

 cular fibre, carrying fringed 

 hairs only known before in 

 Crustaceans (crabs, shrimps 

 and water fleas), and striking 

 the water violently just as do 

 those of the Nauplius. And 

 yet all the while it has on its 

 head a pair of large ciliated 

 wheels which serve it just 

 as do those of the com- 

 mon Rotifer. No Crustacean, 

 young or old, has this " wheel- 

 apparatus '' nor any vibratile 

 " cilia " on the surface of its 

 body. Pedalion possesses an 

 astounding "blend" of char- 

 acters. Fig. 35 shows, besides 

 the "paddles" or "legs" (of 

 which two on the other side 

 of the animal are not seen), 

 the broad and large wheel- 

 apparatus W (within which 

 the right eye-spot r.e. is seen), 

 and a little lobe (^p) called the "chin" lying just below 

 the mouth {m). The big leg (z/./.) and the pair on each 



Fig. 36.— The Rotifer Pedalion 

 mirum — seen from the ventral 

 surface. Letters as in Fig. 35. 

 The complete fan of eight fringed 

 hairs terminating the great vent- 

 ral limb are seen, and the three 

 spine-like processes on each side 

 of it. The fringed hairs of the 

 two ventro-lateral limbs, l.l.^, are 

 omitted ; they are fully shown 

 in Fig. 35, and are the same in 

 number and disposition as those 

 forming the "fan" of the great 

 ventral limb. Compare these 

 hairs with those of the "Nauplius " 

 Crustacean larva drawn as a tail- 

 piece to Chapter XIII. 



