FIONA. 77 



and the clubs are laminated ; the oral tentacles or feelers arc 

 very long, and the branchiae are linear, and crowded in cross 

 series along the sides of the back ; the caudal extremity is 

 slender and greatly extended. 



Species of Phidiana. 



Inca, D'Orb. Northumbrica, Alder and 



longicauda, Quoy and Gaim. Hanc. 



Patagonica, D'Orb. 



Genus CALLIOPiEA, D'Orbigny. 



Head without tentacles ; labial feelers very long and taper- 

 ing. Gills pyriform, placed in longitudinal lines. Front of 

 foot angular. 



Ex. C. bellula, D'Orbigny, pi. 06, fig. 7. 



The obvious and striking peculiarity in this beautiful Nudi- 

 branch is the entire absence of the dorsal tentacles, in which 

 it resembles Alderia, but the vent does not appear to be 

 dorsally situated ; the eyes are conspicuous on the back of 

 the head. 



Genus FIONA, Alder and Hancock. 



Tentacles four, sub-dorsal, without sheaths ; mouth with 

 corneous jaws. Gills papillary, on sub-pallial expansions 

 on the sides of the back, meeting posteriorly ; papilla) with a 

 membranous fringe on the inner sides. 



Syn. Oithona, Alder and Hanc, not Baird. 



Ex. F. nobilis, Alder and Hancock, pi. 67, fig. 1. 



The principal peculiarity in this genus is the fact of the 

 branchial lobes each having a membranous fringe with a 



VOL. II. M 



