254 MORPHOLOGY OF INVERTEBRATE TYPES 



tractors. Open its lower wall along the median line and fasten 

 the sides down with pins. Make a drawing showing the in- 

 fundibular valve, the four organs of Verrill and the retractors. 



1 8. Remove the nidamental and accessory nidamental glands, 

 the nephridial sac and the body wall. When this has been done, 

 pass the end of a curved forceps between the posterior vena 

 cava of each side and the corresponding lateral mantle vein, 

 and separate the vessels without tearing them. In a similar 

 manner separate the ink-sac from the rectum leaving intact its 

 attachment to the anal chamber and push the ink-sac to your 

 right. Separate the oviduct from the underlying tissues. Push 

 the stomach pouch to the left exposing the ovary and the oviducal 

 gland. Observe the cephalic retractors exposed to view by the 

 previous removal of the funnel, the oesophagus and the liver be- 

 tween the retractors, and the two large stellate ganglia situated on 

 the mantle under the retractors on the level of the tips of the 

 gills. Find the single splanchnic ganglion on the rectum near its 

 base. Make a full page drawing of all organs as exposed to view. 



IQ. Remove the posterior venae cavae and the urinary gland 

 together with the nephridial arms of the anterior vena cava 

 passing through them, thus exposing the systemic heart. Cut 

 the sheet of integument which fastens the right gill (on your left) 

 to the mantle and turn the gill so as to bring into view the 

 branchial artery which runs from the branchial heart along the 

 gill. Make a drawing showing the branchial hearts, the left 

 branchial vein, the right branchial artery, the systemic heart, 

 the base of the anterior aorta and the posterior aorta with the 

 three mantle arteries. 



20. Remove the arterial system (except the anterior aorta), 

 branchial hearts and gills. Carefully push to the left the di- 

 gestive organs, thus exposing to view the female reproductive 

 organs. Make a drawing showing the immense ovary and the 

 oviduct. In the latter show the first portion, the second portion 

 or oviducal gland and the last portion with the genital opening 

 not far from the anus. 



