HuTTON. — On the Bitentaculate Slugs of New Zealand. 161 



Excretory and circulatory systems (fig. 15). The pulmoBary cavity is 

 closed internally by a delicate membrane, slightly radiately plicated, and 

 lies centrally in the animal. The heart is immediately to the left, and out- 

 side it. The ventricle is yellow, the auricle colourless. The aorta divides 

 immediately into anterior and posterior branches. The renal organ is 

 double, and lies behind the pulmonary chamber. The duct from the right 

 organ passes over to the left, where it joins the duct of the left organ, and 

 both open by a common duct into the respiratory cavity. 



Nervous system (fig. 6). This is very compact and concentrated. The 

 parieto- splanchnic and pedal ganglia are in contact, but not fused together. 

 The whole nerve collar is white. The right peduncular nerve passes over 

 the oviduct, close to the genital opening (fig. 7 h). The auditory vesicles 

 are placed on the outer margins of the pedal gangUa. 



EXPLANATION OF PLATE V. 

 Fig. 1. Janella marmorea, natural size. a. pulmonary orifice ; h. anus ; c. 



opening of reproductive organs ; d. eye peduncles ; e. mucous pore. 

 Fig. 2. The same. Section across body after having been in spirit, showing the 



three-grooved foot. 

 Fig. 3. The same laid open. a. buccal mass ; b. penis ; c. ovo-testis ; d. vas 



deferens ; e. hermaphrodite duct ; /. albumen gland ; g. rectum ; li. 



stomach and intestine ; i. liver ; h. pulmonary opening. 

 Fig. 4. The same ; buccal mass from the side. a. buccal mass ; h. oesophagus ; 



c. odontophore ; d. organ of Semper. 

 Fig. 5. The same ; alimentary system, a. buccal mass; h. commissure of cerebral 



ganglia; c. salivary glands; d, rectum; e. liver; /. posterior branch 



of aorta. 

 Fig. 6. The same ; nerve collar, a. commissure of cerebral ganglia ; h. eye 



peduncle retracted ; c. auditory vesicle. 

 Fig. 7. The same ; reproductive system, a. ovo-testis ; h. hermaphrodite duct ; 



c. albumen gland ; d. oviduct ; e. vas deferens ; /. penis ; g. sperma- 



theca ; h. peduncular nerve ; i. opening of reproductive organs ; k. 



retractor muscle of penis. 

 Fig. 8. The same ; radula laid open, magnified five times, a. anterior end ; the 



dotted lines show the direction of the transverse rows of teeth. 

 Fig. 9. The same ; central tooth, magnified 700 times. 

 Figs. 10 and 11. Janella papillata ; central teeth magnified 700 times. 

 Fig. 12. Janella bitentaculata ; central tooth magnified 700 times. 

 Fig. 13. The same ; lateral tooth, magnified 700 times. 

 Fig. 14. Side view of the last. 

 Fig. 15. The same ; excretory system, from below, a. pulmonary chamber ; 



b. heart ; c. anterior branch of aorta ; d. posterior branch of aorta ; 



e. renal organ ; /. anus. 

 Fig. 16. The same : rudimentary shell, from below, a. respiratory orifice ; 6. cal- 

 careous plates forming the shell. 



18 



