CERTAIN GROUPS OF ARTICULATA. 275 



Not only from its form and habit is it entitled to be called a 

 parasitic worm, but also because its internal organization is in a 

 large degree like that of the true intestinal worms. On this 

 account the group to which it belongs, the Rotifera (L, N, O), 

 is most decidedly affirmed by some naturalists to be allied in 

 every respect to the Worms ; but there are others who are equally 

 tenacious in their belief that they should be classed with the 

 Shrimps (Cyclops, &c. P), Lobsters, and Crabs. This they urge 

 upon the ground, that, although some of the Rotifers are worm- 

 like in form, others, and the majority of them, have a more or less 

 hardened shell, (O, s, s 1 , s 2 ,) which in a large number of cases is 

 nearly as broad as long, like that of Lobsters and Crabs; and 

 that they produce a peculiar brood of eggs, known as the 

 " winter-eggs" which they carry around with them attached to 

 the outside of the shell, in the same way as the Cyclopida? (P). 

 I come no\v to an animal, Myzostoma, represented by this 

 figure, (H,) which of all creatures known presents the most 

 puzzling combination of characters, not only externally, but also 

 in its internal organization. It lives as a parasite upon a species 

 of Star-fish. If we consider its general form, in connection 

 with its five pairs of jointed, foot-like appendages, (c/,) which are 

 tipped by hooked claws, or bristles, its stomach, (ph to an,) to 

 which are attached numerous, irregularly branching appendages, 

 (v, v 1 , v 2 ,) and the union of the male and female organs of repro- 

 duction (ov to ov 4 , and pe, pe 1 , p 2 , w, w) in the same individual, 

 we are reminded of the Tardigrada (I) ; or if we add to these 

 characters the highly concentrated nervous system (n), and the 

 remarkable similarity of its young to those of the Mites, we can- 

 not fail to see its close resemblance to the latter. But if again 



a 



we take into account its protrusile proboscis, (w 1 ,) in connection 

 with the branching stomach, (ph to an and v, v l , v 2 ,) its peculiar 

 organs of reproduction, which are both male (ov, ov 1 , ov 2 , ov*, ov 4 ) 

 and female (pe, pe 1 , pe 2 , w, w), and its four pairs of adhering 

 suckers (sk, sk l , sk 2 ) ranged along the under side of the body, 

 we are led to refer it to the same group as the Planarice (M), 

 or some of their vermine congeners, e. g. Prostomum (K), or the 



