572 APPENDIX 



d. Turn back left mantle-lobe. Note : foot ; labial palps ; gills, 



line of attachment of outer gill to mantle, siphons (Fig. 222). 



e. Pin back labial palps and gills of left side. Note : attach- 



ment of inner lamella of inner gill ; seeker passed between 

 foot and free middle part of inner gill into epibranchial 

 chamber and out at dorsal siphon. Left kidney and genital 

 openings exposed by cutting through attachment of inner 

 gill plate to foot (Fig. 223). 



3. In end views of animal note : mouth, labial palps (Fig. 226 B) ; 



siphons, cloaca, anus. 



4. Remove carefully dorsal wall of body, thus opening pericardium. 



Note : rectum ; ventricle, auricles (Fig. 408). 



5. Cut through auricles and hinder end of rectum and turn latter 



forwards. Note : renopericardial openings. Cut through 

 floor of pericardium on one side, thus opening non-glandular 

 limb of kidney. Note : opening to exterior ; glandular 

 limb of kidney ; visceral nerve-commissures. 



The alimentary canal should be studied in a specimen in 

 which it has been injected and dissected out (Fig. 228). 

 8. Find nerve" ganglia — cerebral by gently scraping skin behind 

 anterior adductor, pedal by cutting vertically through 

 muscular part of foot and separating the halves, parieto- 

 splanchnic by viewing ventral surface of posterior adductor. 

 10a. Remove from its shell a spirit-preserved specimen. With a 

 sharp scalpel make the following sections : (1) through middle 

 of foot, (2) through hinder part of foot, (3) behind foot. 

 Note: attachments of gills (Fig. 225); internal organs in 

 transverse section (Fig. 227. The first section will probably 

 not show the heart). 

 Specimens of Amphioxus may be obtained from dealers. 



2a. In a left side view, note : mouth, oral cirri ; 

 The Lancelet. anus; atriopore ; myotomes; dorsal, caudal, 



and anal fins (Fig. 233). 

 b. In a ventral view, note : ventral groove ; metapleural folds ; 

 mouth, etc., as before (Fig. 234). 



4. In a specimen which has been macerated for twenty-four hours 



in 20 per cent, nitric acid, remove the wall of the atrial 

 cavity on the right side. Note : mouth, oral cirri, pharynx, 

 gill-slits, liver, intestine, anus ; notochord ; spinal cord ; fin 

 rays ; generative organs. 



5. Remove and stain the hind end of the pharynx, slitting it open 



dorsally and flattening it. Note : primary and secondary 

 bars, skeletal bars, synapticulae, developing slits (Fig. 238). 

 8. Remove the spinal cord by shaking the macerated specimen in 

 a test tube with water, stain, and mount. Note : eye spot : 

 first pair of nerves ; dorsal and ventral nerves ; cerebral 

 vesicle, central canal (Fig. 244). 

 10. In transverse section, note : in the pharyngeal region, 

 myotomes ; notochord and its sheath ; spinal cord ; 

 pharynx, gill-slits, endostyle, dorsal groove ; ventral aorta 

 and suprabranchial arteries ; atrial cavity ; ccelom ; gonads ; 



