AXATOMV AND DEVELOPMENT OK THE ECHINODERMS 121 



I'ig. 5. Tonmria, probably and Asteiias- 



larva VL The corresponding diagram. 



YK'g. (>. \ Aiinciilaria, \}as Holothiiria-larva in VIL^ -i^-.j 



Eig. 7. I, its two forms VIII.J 



In all the figures of larviv the mouth and anus are indicated by the letters m and a, and 

 the cilia are disproportionately large so as to render the " fringes " and " bands" evident. 



The Diagram No. I. is similarly lettered, and all the other diagrams have their anterior 

 and posterior extremities in a position corresponding to it. 



Eig. 8 is the larva of A^»«f«/H.r after Max. MiiUer. 



Eig. 9. The larva of an Annelid after Milne-Edwards. 



Eig. 10. Aiiricidarta. The larva of Holothuria, after Midler ; to show the mode of develop- 

 ment of the water-vascular system, &c. from the internal bud, d: e, the oval 

 masses of cells. 



Eig. II. One of the epauletted Echinus-larva;, in which the Echinoderm, d, has already 

 begun to envelope the stomach of the larva. 



IX. X. XI. XII. XIII. are diagrams intended to represent the mode of development of an 

 Asterias within its larva, the Bipinnaria. 

 The form of the latter is not given ; its relation being indicated only by the dotted line. 



IX. lit, the mouth of the larva ; a, its anus ; d, the bud-like commencement of the Echino- 



derm. 



X. XI. The latter has developed the water-canals, and with its accompanying blastema has 



begun to invest the stomach of the larva. 



XII. The investment nearly complete. The position of the mouth of the Asterias indicated 



by (0). 



XIII. The Echinoderm has become free and separate from the body of the larva with its 



primitive oesophagus. 



It is to be understood that these diagrams do not pretend to be strictly accurate. They 

 are intended only to render the process of development more easily comprehensible. 



