CERTAIN GROUPS OF ARTICULATA. 273 



not only on account of its shape, but also because it lives in the 

 intestines of a serpent, the Boa - constrictor ; but, by the re- 

 searches of Van Beneden, it was ascertained that in the youngest 

 stage of growth, just at the period of hatching from the egg, it 

 has the form represented here (B). This at once convinced its 

 discoverer that the Linguatula is not a worm ; but yet it does 

 not appear to have proved the relationship of the animal to any 

 particular group ; for although Van Beneden says that the young 

 have a close affinity with those of Anchorella, an animal well 

 known to be a Shrimp, he is not positive as to this relation- 

 ship ; and, on the other hand, there are naturalists who think 

 that the young Linguatula exhibits fully as much the characters 



Fig. 180 (K). Prostomum lineare. (Est. For the lettering and description 

 seep. 36, fig. 19. 



Fig. 181 (L). Albertia vermiculus. Duj. 100 diam. A view from below, 

 m, the mouth ; j, the internal jaws ; c, glands attached to the sides of the throat, 

 probably for the purpose of applying saliva; p, the throat; g, lateral pouches of 

 the stomach; ct>, the vessels of the aquiferous circulatory system; e, e l , the 

 eggs ; in e l the young is far advanced in development ; t, the tail. From Du- 

 jardin. 



Fig. 182 (M). Dendroccelum lacteum. (Est.? 3 diam. For the description 

 of the lettering see p. 92, fig. 47. 



Fig. 183 (N). Conochilus volvox. Ehr. From fresh water. Natural size 

 0.260 millimetre long. A worm-shaped Rotifer, Ib, the cilia-bearing lobes of 

 the head; an, the feelers ; t, ft, the tail ; m, the mouth ; ml, cavity of the mouth ; 

 /, the jaws; st, st 1 , s< 2 , the three apartments or subdivisions of the stomach; 0, 

 the pair of eyes ; eg, an egg ; ms, longitudinal muscles used to retract the body 

 into the gelatinous sheath in which the animal lives. From Cohn. 



O 



Fig. 184 (O). Squamella oblonga. Ehr. 200 diam. From fresh water. A 

 view from below of a Rotifer which has a distinct shell or carapace (s, s 1 , s 2 ). 

 s, the anterior transverse edge of the carapace ; s 1 , the anterior, and s a , the pos- 

 terior corners of the carapace ; s 3 , the border of the oval, flat area which occu- 

 pies the lower face of the carapace ; lb, the cilia-bearing lobes of the head ; /, 

 the fork of the tail (J 1 ) ; m, the mouth: j, the jaws; j l , muscles which move j , 

 st, the stomach ; cv, the contractile vesicle, or heart of the aquiferous circulatory 

 system; cf 1 , cr 2 , the right, and ct' a , ct? 4 , the left aquiferous circulatory vessels; 

 eg, eg 1 , and er/ 2 , two largely developed young. Original. 



Fig. 185 (P). Cyclops quadricornis. Mull. 50 diam. For the lettering 

 and description see p. 220, fig. 128. 

 18 



