NOTODELPHYS. 239 



of three joints, and having the seta? which spring from 

 them partially plumose. 



The feet are four pairs in number, and are all alike (f. 1 y}. 

 They consist, each of two branches, springing from a basal 

 lamina of two joints, and each branch composed of three 

 articulations, copiously furnished on their inner edge with 

 plumose seta3. Each of these feet is attached to a cor- 

 responding segment of the thorax. 



The abdomen is somewhat cylindrical, and terminates 

 in two caudal appendages, each carrying at the extremity 

 four short, plumose setas. The fourth segment of the body 

 is of a peculiar formation, having in its dorsal portion a 

 large hollow receptacle for receiving and containing the 

 ova. In the angle between this sac and the upper surface 

 of the ring, of which it forms a part, there is an opening 

 by which the eggs escape when they have arrived at 

 maturity. At first emerging from the ovum the young 

 animal is very like in form to the young of the Cyclops ; 

 but its changes have not been traced from this larva state 

 to its full growth. 



Halt. Belfast Bay ; Strangford Lough, county Down ; 

 W. Thompson and G. C. Hyndman, Esqrs. Killery 

 Bay, county Galway ; R. Ball and W. Thompson, Esqrs. 

 Bangor, county Down ; R. Paterson, Esq. Glandore 

 Harbour, county Cork, Dublin Bay, and Southampton 

 Water; George J. Allnian, Esq. In the branchial sac of 

 the Ascidia communis. 



