118 



ANIMAL PHYSIOLOGY. 



[LESSON 33. 



FIG. 197. 



so called usually with the addition of the name of its discoverer, 

 Poli thus : ampulla Poliana), or belong to the 

 reproductive function, is difficult to say most 

 likely the latter. Out of four animals of this 

 species dissected, and made into preparations 

 (which exist), no trace of tentacula was found 

 in either of them. 



The muscular system in these animals, like 

 that of Holothuria, is powerfully developed. 

 It is arranged (as already shown) in longitudi- 

 nal parallel fibres, whilst the head can be re- 

 tracted by a very strong tendon, attached to it, 

 and inserted by a broad expanded base, below 

 the lower third of the animal's body. 



A view of the muscular system, dissected 

 out of the integument, is given in Fig. 197. 

 The muscles are described at a, and the tendon, 



above referred to, at b. 



Muscular system, Sipun- 

 culus. 



XXXIII. 



ORGANS OF NUTRITION IN THE ANNELLATA. 



550. The Latin name which distinguishes this class is derived 

 from anellus, a little ring, the bodies of all the individuals belonging 

 to it being composed of a series of little rings, or segments. 



551. A peculiarity of this class is, that they all possess colored 

 blood, generally red, although in some species it is yellowish ; from 

 this circumstance they are very usually called " the red-blooded 

 worms." Many of these animals are Terrestrial (belonging to the 

 earth), as the common Earth-worm (Lumbricus terrestris), or Angle 

 worm, but by far the greater number are inhabitants of the ocean. 



552. The most attractive portion of the structure of a majority 

 of the marine worms, is the respiratory tuft, which is placed (in 

 some species) at the summit of the head. A very common marine 

 worm is the Serpula contortuplicata, a figure of which is given 

 (Fig. 198). 



553. When all is quiet, and the creatures are luxuriating in 



