284 Mr. T. Austin on the Connexion between 



if taken into the calculation would swell the number to upwards 

 of a million. And if we consider the number of muscles requisite 

 to put this million of parts in motion, we are lost in admiration 

 at the apparent complexity, but in reality simplicity of structure 

 in the indurated skeleton of this animal. 



For the better comprehension of this important and interesting 

 gi'oup of animals it is desirable to enter into some detail respect- 

 ing the whole tribe of Echinoderms, a term applied by Bruguiere to 

 those animals whose skin is generally furnished with calcareous 

 spines. Accordingly the Star-fishes or Asteriadce are first noticed. 

 These animals are enveloped in a coriaceous integument studded 

 in various degrees with granules of calcareous matter. They 

 present different modifications of form, and according to that 

 form depend in a great degree the characters which have enabled 

 naturalists to divide them into various genera and species. 



The genus Goniaster may be described as an animal of a pen- 

 tangular form ; on the inferior surface and on a line with the 

 angles run five furrows or depressions, on the margins of which 

 are numerous foramina, through which protrude the tubuliforra 

 tentacula, which are furnished with cup-like appendages. These 

 may be considered as the feet, as they are the only locomotive 

 organs possessed by animals of this genus. 



The true Asterias are known by their simple flattened rays, 

 which are generally five in number, but some species have as 

 many as ten or twelve. All these have the mouth placed beneath, 

 around which are several perfoi-ated plates ; these perforations 

 are known to be the ovarial passages. There are other openings 

 which probably aid in the purposes of respiration, as well as in 

 the water circulation, as they lead to the canals known as the 

 aquiferous system. The term ^oviducal plates^ has been applied 

 to the pieces through which the ovarial apertures pass. 



Next, the Ophiura may be known by a small orbicular disc-like 

 body, from which emanate five circular attenuated rays. These 

 are in many instances furnished with spines which aid them in 

 locomotion. 



The Euryale, or Gorgonocephalus of Leach, bears some resem- 

 blance to the Ophiura ; but in place of the five simple rays, each 

 of its rays branches off into so many subdivisions, that 512 have 

 been counted as given off by each ray, which multiplied by 5, 

 the number of the parent rays, gives 2560 lesser subdivisions or 

 filaments capable of forming a net for the capture of food, and 

 also by its undulatory motion of producing progression through 

 the water. By means of these filaments the Ewijale can attach 

 itself to extraneous bodies, such as Gorgonice, and thus moor 

 itself in order to repose, or as a protection against the violence 

 of an agitated sea. 



