The anatomy of Lucapina crenulata. 



479 



Mad radula 



Had. s radula supports 



R.i.p right internal palliai nerve 



Mm. n retractor muscles nerve 



M. P reno-pericardial duct 



M.S.n nerves to radula sheath 



Sg sugar glands 



Sg.n sugar gland nerves 



Si stomach 



Suh subintestinal nerve 



Suh.g subintestinal ganglion 



Sup supraintestinal nerve 



Sup. g supraintestinal ganglion 



T tentacle 



ta ciliated fringe of lips 



T.n nerve to tentacle 



Up upper palp 



TJ.p.n unpaired pedal nerve 



Vis visceral cavity 



Vis. g visceral ganglion 



All drawing are natural size, unless otherwise stated. 



Plate 31. 



rig. 1. The whole mantle is removed so as to show the position 

 of the digestive system. The liver is colored, and is seen as by trans- 

 parency of the organs. The sugar glands are removed so as to show 

 the nerves in the head region. The visceral loop of the nerve is also 

 shown, i/g. 



Fig. 2. Visceral cavitj'- showing position of genital mass. The 

 mantle cavity is seen in the anterior part, the dorsal wall and ctenidia 

 having been removed with the shell. This figure also shows the muscu- 

 lar diaphragm between the visceral cavity an the head region, ^j^. 



Fig. 3. Veins on the inner surface of the foot. The walls of the 

 visceral cavity have been largely cut away in order to show all the 

 branches of these vessels. The three large veins cut in the anterior 

 end of the cavity unite dorsally in the basibranchial sinus, ^/g. 



Fig. 4. Pericardial cavity. The heart, with the section of the 

 rectum that passes through it, has been removed, so as to show the 

 position of the left nephridium (L. n). 2:1. 



Plate 32. 



Fig. 5. A median cross-section of the osphradium. The ganglionic 

 cells (6r. c) are seen scattered around the periphery of the chord, and 

 also wedged in between the columnar cells of the surface. Several 

 large multipolar cells [Mp) found in the series of sections. Greatly 

 magnified. 



Fig. 6. Mouth, pharynx, and a part of the oesophagus laid open 

 from the dorsal side, to show the glandular structure and general ar- 

 rangement of parts, ^/g. 



Fig. 7. A few of the varied shapes assumed by the blood corpus- 

 cles. (I) is a corpuscle that has been stained showing the large nucleus 

 in). All greatly magnified. 



Fig. 8. Shows relation of the oviduct (G.d) to the external opening 

 of the right nephridium {Exr), which is here seen from the inside. 



Fig. 9, Auriculo-ventricular valve from the side of the auricle, 

 X, y and z designate parts of the valve. 3 : 1. 



