502 EXPLANATION OF THE PLATES. 



75. Pecten varius, Linn, m, fringed mantle borders ; 6r, 



branchiae, 18, 105 



16. Lepton squamosum, Mont. Showing the mantle fringes, 78 



77. Pedal ganglia of Helix pulchella, Miill. a, ganglia; o, 



otocysts ; 6, profile view of an otoeyst ; c, otolites. 

 (Leidy, Binney's Terr., Moll.), . . . . 71, 78 



78. Otoeyst of Cyclas. o, single otolite ; c, ciliated epithelial 



cellules (Leydig), 79 



79. Lamellar tentacle (rhinophore) of Eolis coronata, Forbes 



(Alder and Hancock), 75, 79 



Plate 7. 



80. Circulating and respiratory organs of Nautilus Pompi- 



lius. (After Owen.) 1. The great vein. 1'. The orifices 

 by which it communicates with tlie abdominal cavity. 

 2. The venous sinus. 3. Splanchnic veins from the liver, 

 ovarj^ gizzard, etc. 4. Origins of the branchial 

 arteries. 5. Branchial arteries. 6. The follicles ap- 

 pended to the branchial arteries. 7. Orifices by which 

 they communicate with the branchial arteries, ex- 

 posed on the left side (the parts being seen from the 

 dorsal aspect). 8. The valve at the entry of the 

 branchial arter^^ into the gill, exposed in the right 

 anterior vessel. 9. Cavity of the same arter}^, w^here 

 it is imbedded in r, the muscular stem of the gill laid 

 open. p. The larger branchia of the right side, 

 showing the venous surface, p'. The same of the left 

 side, showing the venous surface, q. The smaller 

 branchia of the right side, showing the arterial sur- 

 face, with r, the fleshy skin entire, the dotted line 

 indicating the passage of the branchial arter}^ into it. 

 q'. The smaller branchia of the left side. *•. TJie 

 common stem of the branchiae, by which they adhere 

 to the inner surface of the mantle. 10. The branchial 

 veins. 11. The valves placed at their terminations in 

 the ventricle, t. The ventricle or sj'^stemic heart, 

 laid open. 12. The origin of the lesser aorta. 13. 

 The artery of the glandular ovai'ian apparatus. 14. 

 The siphonic artery. 15. The artery of the intestine. 

 16. The larger aorta. 16'. Its muscular origin or 

 the continuation of the ventricle. 17. The valve at 

 the extremity of this part, . . . . 83, 88 



81. Branchiae of Octopus. (Cuvier, Mem. Moll. Ceph.) 



mbr. Branchial muscle, vbr. Branchial vein, w b r. 

 Arterial nerve. v c. Yena cava. c b r. Branchial 

 heart, ab r. Branchial artery, .... 83 



