ON THE ORIGIN AND 



[CHAP. 



Fig. 40 represents a larva, probably of another sea- 

 egg (Echinus lividus), from the Mediterranean, and 

 shows the commencement of the sea-egg within the 

 body of the larva. The capital letters denote the 

 different arms ; a is the mouth, a the oesophagus, b 



FIG. 40, Larva o Echinus, x 100. A, front arm ; F, arms of the mouth 

 process ; B, posterior side arm ; E^ accessory arm of the mouth pro- 

 ces* ; , mouth ; ',oesophagus ; b, stomach ; b', intestine ; <?, posterior 

 orifice ; d, ciliated bands ;_/", ciliated epaulets ; c, disc of future Echinus 

 (after Miiller). 



the stomach, b' the intestine, f the ciliated lobes or 

 epaulets, c the young sea-egg. 



The development of the beautiful Comatula rosacea 

 (Fig. 41) has been described in the " Philosophical 

 Transactions," by Prof. Wyville Thomson and Dr. 

 Carpenter. 1 The larva quits the egg, as shown in 

 Fig. 42, in the form of an oval body about Jg inch 



1 Philosophical Transactions, 1865 and 1866. 



