NTTDIBEANCHIATE MOLLUSCA FEOM THE EASTERN SEAS. 133 



Branchiae consisting of about seven compound leaflets, each separately retractile. Head 

 with a bilobated crenated veil. 



I have named this genus after the late If r. Albany Hancock, a gentleman so well 

 known in connexion with the history of these animals. For euphony's sake I have so 

 adapted the name as to make it agree with Formosa, the native island of this elegant 

 species. The genus must be placed near BZexabranchus. 



Albania Formosa, Coll., n. sp. (Plate X. figs. 1-5.) 



Length 2 inches. Body extremely delicate, almost semitransparent. Mantle broad 

 and capacious, forming, as it were, wings or fins on either side ; the edges turned over the 

 back when at rest. Dorsal tentacles large and rather thick, consisting of a conical, 

 bluntly pointed, finely laminated portion, with the commissure anterior, mounted upon 

 a cylindrical pedicle of equal length, without a sheath, non-retractile. Branchial con- 

 sisting of seven compound leaflets, each having three or four or five branches, and arising 

 from a common thick pedicle, but separately retractile, the whole forming a ring near the 

 posterior extremity of the mantle ; very delicate and almost transparent. Head with a 

 bicrcscentic veil, and studded round with a fringe of minute papilla?. Foot extending 

 j inch beyond the mantle posteriorly, somewhat rounded. 



Colour and general appearance. — General tint a pale rose, darker and richer on the 

 back, forming a Vandyke pattern nearly regular on either side. Edge of the mantle 

 opaque white, with a wide inner border of crimson, the whole studded with minute 

 whitish translucent points, the greater or lesser abundance of which effects the gradation 

 of colour. Laminated portion of the tentacles crimson ; pedicles pale rose. Fringe of 

 the veil orange ; veil and posterior portion of the foot yellowish ; under surface pale rose. 



One specimen of this singular and beautiful Nudibranch was taken in a red sandstone 

 rock-pool in Ke-lung Harbour, North Formosa, May 31st. When placed in a vessel of 

 sea-water it commenced swimming freely with a vertical vermicular movement and 

 extreme grace. The mantle was spread out wide, the tentacles thrown back, like ears, 

 ind the anterior and posterior extremities of the body thrown upward till they met above, 

 lien partially thrown back, the mantle waving in a vermicular manner from anterior to 

 posterior edge. It continued swimming like this for a considerable time. It did not 

 :rawl about like other Xudibranchs, but when not swimming remained in a more or less 

 contracted form, the mantle constantly changing its aspect. When, however, I turned 

 It over, it floated on its back like its congeners. I have called the species Jbrmosa, both 

 I roni its beauty and the island of which it is a native. 



Family POLYCERID^], Alder & Hancock (1855). 

 Genus Triopa, Johnston (1838). 



tsiopA Princlpis-Walll^, Coll., n. sp. (Plate X. figs. 6-11.) 



Length f inch. Body slender, narrow, rounded in front, obtusely pointed behind. 

 'lantle scanty, just covering the body, smooth, and furnished with papilla; round the 

 nterior portion and along the sides. The anterior papilla?, eight in number, arranged 



18* 



