PLATE XXIX. 



Class-CEPHALOCHORDA. 



THE LANCELET (Amphioxus lanceolatus). 



FIG. 1. AMPHIOXUS : VIEWED AS A TRANSPARENT OBJECT, x 2. 



m. mouth with cirri : p. pharynx : r. reproductive glands : I. liver : 

 a. p. atrial pore : i. intestine : a. anus : nt, notochord : n. 

 spinal cord : s. septa between the myotomes. 



FIG. 2. HEAD, x 6 T . 



nt. notochord : e. eye : n. spinal cord : s. septa between the myotomes : 

 r. cartilaginous rod bearing cirri : L lobes of the pharynx : 

 a. branchial arches. 



FIG. 3. TRANSVERSE SECTION THROUGH THE REGION OF THE LIVER, x 10. 



/. skeleton of the dorsal fin : n. spinal cord : nt. notochord 

 surrounded by its sheath : a. 1 dorsal aorta : g* hyperbranchial 

 groove: I. liver: o. ovary: g. z hypobranchial groove: a. 2 

 ventral aorta : p. cavity of the pharynx : I. branchial arches. 



FIG. 4. TRANSVERSE SECTION PASSING THROUGH THE ANUS, x 10. 



/. dorsal fin : n. spinal cord : nt. notochord : a. dorsal aorta : 

 i. intestine : an. anus : v. ventral fin. 



