riRST APPEAEAyCE OF THE STAEFISH. 3] 



ment of Echinaster. -where the whole Lirva and all its appendages are 

 gradually drawn into the bod}-, and appropriated during the growth of 

 the young Stai-fish. 



It has alread}' been shown that the anal portions of the water-system, 

 as they increase in size, spread little by little over the surface of the 

 stomach ; the edges creeping towards each other and surrounding the 

 stomach on both sides, like a cap, yet without miiting. The funnel leading 

 from the dorsal pore shortens as the water-system extends towards the 

 dorsal region, and the anal extremities of the water-tubes come so near 

 together (PI. V. Figs. 1, 2, 3, 5, w, ?//) that we might almost be tempted 

 to believe the}- join, like the oral portions, and thus form a complete 

 circuit (PI. m. Fig. 10) ; this, however, is not the case, as an examina- 

 tion in profile of the above figui-es readily shows. 



First Appearance of the Staijish. — In the drawings here given to illus- 

 trate the development of the Starfish, only a small portion of the Brachio- 

 laria is figured, that which has direct reference to the Starfish itself; as 

 this part is limited to the anal extremity of the larva immediately sur- 

 rounding the stomach, the anal extremity alone of the Brachiolaria is 

 drawn, with the arms cut ofi", somewhat beyond the opening of the anus. 

 To make the references to the figures of Plate V. more satisfiictory, a 

 reference has also been made to a drawing of a whole Brachiolaria, in 

 a stage of growth nearly identical, in order to show more readily the 

 relation of the Starfish to the whole framework of the Brachiolaria. 

 Tliese stages are so similar that, with this explanation, it will always be 

 possible to refer the anal extremities, upon which we are tracing the 

 development of the Starfish iu its diflerent phases of growth, to some 

 figure of Brachiolaria, very nearly representing its actual condition. The 

 stages of development figured in Plate V. have been selected simply 

 for the sake of the young Starfish, without reference to the Brachiolaria, 

 and would, if drawn on the same scale as the other figures of the 

 Brachiolaria here given, show no differences, which would make the mode 

 of growth of the vouno- Echinoderm more intelliorible. For instance, the 

 earlier stages of the development, such as Figs. 1-7, correspond to the 

 stage of PL III. Fig. 10 ; while the more advanced Fig. 8 corresponds to 

 that of PI. in. Fig. 11, and the others to the adult stages of the Brachio- 

 laria on Plate IV., when the Starfish undergoes extensive changes, while 

 none take place in the general appearance of the Brachiolaria. 



