tritoniad^. 381 



Suborder AIOLOBRANCHIATA. 



Branchise variable, generally upon the sides of the back ; not 

 as in the last family, in a circle surrounding the anal orifice. 



Family TRITONIAD^. 



Animal with laminated, plumose, or papillose gills, arranged 

 j^long the sides of the back ; tentacles retractile into sheaths ; 

 lingual membrane with one central and numerous lateral teeth ; 

 orifices on the right side. 



Tritonia, CuAder. 



Syn. — Candiella, Gray. 



Distr. — 20 sp. Northern seas, Polynesia, Red Sea. Under 

 stones at low-water to 25 fathoms. T. Homhergii^ Cuvier, found 

 on the English scallop-banks, attains a length exceeding 6 inches. 

 T. plebeia, Johnst. (xc, 14), 



Animal elongated ; tentacles with branched filaments ; veil 

 fimbriately digitated ; gills in single series on a ridge down 

 each side of the back ; mouth armed with horny jaws ; stomach 

 simple, liver compact. 



MARiONiA, Yayssiere, 18Y9. Body elongate, sides compressed, 

 mantle none ; velum small, ramose, in a dorsal line ; maxillae cor- 

 neous ; stomach armed with cultriform teeth. T. Berghi, Vayss. 

 Gulf of Marseilles. 



CALTPHYLLA, Costa. Body long, narrow ; tentacles two, folia- 

 ceous, longitudinally convolute; labial border bilobed ; branchiae 

 foliaceous, vascular, numerous, in irregular, longitudinal series ; 

 anus on the right side behind the genital orifice. Distr. — G. 

 Mediterranean Costa. Mediterranean. 



NEMOCEPHALA, Costa. Body Tritoniiform ; anterior margin of 

 the head semicircular, six-digitate, or divided into six simple, 

 cylindrical tentaculiform processes ; tentacles ramose, retractile 

 into sheaths ; branchiae arborescent, on both sides of the back in 

 single longitudinal series. Difi"ers from Dendronotus in the six 

 filaments being simple, not branched. Distr. — T. marmorata, 

 Costa. Mediterranean. 



HANCOCKiA, Gosse. Body linear, scarcely palliate, head pro- 

 duced on each side into a broad, flat, many-fingered veil; dorsal 

 tentacles with laminated bulbs, retractile within sheaths ; 

 branchiae three pairs, foliate, pinnatifid, infolding, remotelj^ 

 situated on the subpalliate margin of the back ; foot linear, 

 grasping. Distr. — T. eudactylota, Gosse. 



Tethys, Linn. 

 Etym. — Tethys^ the sea (personified). 

 (Sy?!.— Fimbria, Bohadsch. 

 Distr — T. fimbriata, h. {xc, 15). Mediterranean. Attains a 



