ANIMAL KINGDOM. 



109 



external vibratile cilia, as in the beroe pileus 

 represented m fig. 32. This figure represents 



careous spines. These animals are for the most 

 part free, but some are fixed, as the crinoid 

 echinoderma, the vascular system is unpro- 

 vided with auricle or ventricle, and the diges- 

 tive canal is seldom furnished with distinct 

 glandular organs. There is sometimes a simple 

 stomach with one aperture and numerous late- 

 ral coeca, and sometimes a lengthened intestine 

 with two terminal openings. Some marine 

 animals without an echinodermatous covering 

 are placed in this class from the similarity of 

 their structure in their more essential organs, 

 as is the case with the holothuria represented in 

 fig. 34. The mouth (a) is here surrounded with 



one of the ciliograde acalephae in which the 

 mouth (a) is directed downwards, and leads, by 

 a narrow oesophagus, to a wide stomach (6), 

 and from this the intestine proceeds straight 

 through the axis of the body to the anus (c) at 

 the opposite pole. The longitudinal nerves (g), 

 as in holothuria, proceed from a nervous ring 

 around the oesophagus. The ovaries (d) extend 

 along the sides of the intestine ; the surface of 

 the body is provided with eight longitudinal 

 bands of pectinated broad vibratile cilia (M), 

 and two long ciliated tentacula (ff) extend 

 from two curved lateral sheaths. (See ACA- 

 LEPH.E.) 



5. Echinoderma, simple aquatic animals, 

 for the most part provided with a calcified ex- 

 terior skeleton or a coriaceous skin, the body 

 for the most part radiated, globular, or cylin- 

 drical, often provided with a distinct nervous, 

 muscular, respiratory, and vascular system. 

 These animals have received the names of echi- 

 noderma, from the spines or tubercles which 

 generally cover their exterior surface, as seen in 

 the annexed figure of the echinus esculentus 

 (Jig. 33.) The mouth (b) is here in the centre 



Fig. 33. 



Fig. 34. 



of the lower surface, 

 and the intestine (b,b.) 

 connected to the shell 

 by a mesentery (c), on 

 which vessels are ra- 

 mified, passes in a 

 convoluted manner 

 upwards to the oppo- 

 site axis where the 

 anal aperture (a) is 

 surrounded by the five 

 openings of the ova- 

 ries (d,d.) The mouth 

 is surrounded with a 

 maxillary apparatus 

 containing five teeth, 

 and the exterior of the 

 complicated and solid 



shell is seen to be provided with moveable cal- 



~o 



m 



ramose tenta- 

 cula (c) and 

 an osseous ap- 

 paratus. The 

 intestine is 

 long, convolu- 

 ted, vascular, 

 supported by 

 a mesentery, 

 and termi- 

 nates in a 

 cloaca (z) at 

 the opposite 

 axis of the bo- 

 dy. The rami- 

 fied internal 

 branchial ( ff) 

 open from" the 

 cloaca ; the 

 great systemic 

 artery receives 

 the aerated 

 blood from the 

 branchiae, and 

 the organs of 

 generation (m) 

 open near the 

 anterior part 

 of the body. 

 The irritable coriaceous skin is supported by 

 five broad longitudinal subcutaneous muscular 

 bands, and five crowded series of tubular mus- 

 cular feet extend from its surface. (See ECHI- 

 NODERMA.) 



The SECOND SUB-KINGDOM Or DIPLO-NEU- 



ROSE DIVISION comprehends four classes of 

 helminthoid animals and the same number of 

 entomoid classes, viz. 



6. Entozoa, parasitic, simple, internal, or fixed 

 animals, for the most part of a lengthened 

 cylindrical form, without distinct organs of 

 sense or any internal skeleton, the mouth or 

 anterior part of the body generally provided 

 with recurved sharp spines, the body generally 

 covered with an elastic white transparent inte- 

 gument, the nervous system seldom distinct, 

 the vascular system without auricle or ven- 

 tricle, without respiratory organs, and with the 

 sexes generally separate. (See ENTOZOA.) 



7. Rotifera, minute aquatic animals with 

 distinct nervous and muscular systems, provided 

 with eyes, lateral maxilla?, a dorsal vessel, an 

 intestine with two apertures, and with vibratile 

 cilia disposed generally in a circular form 



