ECHINODERMATA. 135 



The opening of the mouth is placed in the centre of the space 

 bounded by the four anterior prehensile hooks ; and the alimen- 

 tary canal is a simple tube passing straight through the body to 

 the tail, where the anal orifice is distinguishable. The walls of 

 the intestine have a reticulated appearance, being covered with a 

 kind of glandular net- work, which probably constitutes a biliary 

 apparatus. 



(178.) In a creature thus highly organized we may well expect to 

 find senses of proportionate perfection, and in Lamproglena their 

 existence is no longer doubtful. The eyes are distinctly apparent, 

 of a reddish colour ; but as yet, as in the lowest crustaceans, 

 united into one mass. The antennae likewise, which may be re- 

 garded as special instruments of touch, are well developed ; and, 

 both in number and position, resemble those which characterise 

 the crustacean orders, to which we are thus conducted by almost 

 imperceptible gradations. 



The reproductive organs are entirely similar to those of Adheres 

 already described. Those of the female, represented in the figure, 

 consist of sacciform ovaria, in which the ova are secreted : and 

 from these, when mature, the eggs are expelled through two simple 

 triangular orifices situated on each side of the anus. 



CHAPTER XL 



ECHINODERMATA.* (Cuv.) 



(179.) The last class of beings belonging to the Nematoneurose 

 division of the animal world seems, upon a partial survey, to be com- 

 pletely insulated, and distinct from all other forms of living crea- 

 tures ; so peculiar is the external appearance, and even the internal 

 organization of the families which compose it. The casual observer 

 who should, for the first time, examine a star-fish or a sea-urchin, 

 two of the most familiar examples of the ECHINODERMATA 

 met with upon our own shores, would indeed find it a difficult 

 task to associate them with any other class, or to imagine the affi- 

 nities whereby they are related, either to the simpler animals we have 

 already described, or to more perfect forms of existence hereafter to 

 be mentioned : they would seem to stand alone in the creation, 



* "E%ivos , a hedgehog ; $&/*, the skin. 



