platp: XL 



Fic. ^!. — Veiitial vifw cil' \';im dfi- llut-veii's orKnu. X -• 

 L, vertical laijiiii:i'. 

 N, nerve. 



VF, vertical tissure. 

 W, wall of the i)ocket, oi' atriiiin, into « liidi tbc anterior end of llie ori;an projects cut from its attachment to 



the organ and folded to one Hide. 

 1, 2, 8, nnisclcs of the organ. 

 Fi(i. II. — Ijongitudinal section of \'an der Iloeven's (prgan, taken throiigli tlie meilian vertical tissnre. ^The ventral 

 .side is u]ii>ennost. ) • L'. 

 (i, G, glandular [lortion of the organ. 

 HF, horizontal fissure. 

 L, horizontal lamina'. 

 Kio. II). — Cross section of Van der Hocven's organ takeji just hark of th.- midilU- oi the organ. (The ventral side is 



uppermo.st. ) X -. 

 Fig. II. — Shell oi Xaulilux piiiii/iiliiix. J natural size. 

 20H 



