112 AMERICAN MARINE CONCIIOLOGY. 



tenanted by their singular mollascan inhabitants, thus serve in 

 some measure to enliven the solitude of the ocean. 



Genus DENDRONOTTJS, Alder and Hancock. 



Tentacles clavate, laminated ; front of head with branched ap- 

 pendages ; gills ramose, arranged in a single series down each side 

 of the back. 



J. D. arborescens, Midler. 229. 



(Doris.) Zool. Dan. Prodr., 229. 1780. 

 Triton ia Reynoldsii, Couthouy, Bost. Journ. Nat. Hist., ii. 74, t. 2, f. 1-4. 



1838. 

 Tritonia lactea, Thompson, Ann. Nat. ITist., v. 88, t. 2, f. 3. 

 Tritonia pulchella, Alder and Hancock, Ann. Nat. Hist., ix. 33. 



Body tapering to the tail, which ends acutely ; sides with nu- 

 merous papillae ; head short, depressed, orbicular, supporting three 

 pair of gills; mouth crescent-shaped, papillose, with strong trans- 

 verse folds; jaws angular; tentacula arising from the back of 

 the head, and received into a round sheath, which terminates in 

 five unequal branches; five pair of dorsal gills, all susceptible of 

 being retracted into the body of the animal, leaving in their places 

 small tubercles; rufous brown, occasionally dark brown, wfth 

 patches of white on the back between the branchial tufts ; foot 

 white, diaphanous. 



Length 3.5 inches. 



New England; Northern Europe. 



2. D. robustus, Verrill. Fig. 230. 



Am. Journ. Sci., 1. 405, f. 1. 1870. 



Eastport, Maine; Grand Manan Island. (Eur.) 



Family DOTONLDiE. 



Genus DOTO, Oken. 

 Lehrb. Naturg. 1815. 



Head covered by a simple veil ; tentacles linear, sheaths trum- 

 pet-shaped ; gills clavate, compound, or rough, with whorls of 

 tubercles ranged in a single series on each side of the back. 



The tentacular sheaths have simple margins, and the ovate 

 branchiae are rough with tubercles ; the front of the head is sim- 

 ple, and the foot is linear ; they appear to feed on hydroid zoo- 

 phytes. 



