. MONOGBA-PH OF THE AMPHIKOMACEA. 241 



that these organs are retractile, and that, at times at least, they 

 serve the purpose of prehension. 



Genus II. Lophonota. 



Lophonota, Costa, Ann. Sc. Nat. 2n<i ser. xvi. 1841 ; Grube, Schmarda, 

 Cams, Ehlers, Quatrefages. 



This genus, proposed by Costa for an Annelid found by him in 

 the Bay of Naples, does not seem to have been seen by any other 

 author since his time. It is characterized by having no caruncle, 

 and nothing in the place of tentacle or antennae. It has four 

 eyes, at least it possesses four small black spots in the place where 

 the eyes ought to be. The feet are disposed in one row only, the 

 setae are subulate and simple, and the branchiae are arbuscular, 

 the filiform branches extended in a transverse series across the 

 back. The animal is furnished with a retractile proboscis, which 

 is surrounded with a sort of fringe. 



Sp. 1. LOTHONOTA AUDOTJINII. 



Lophonota Audouinii, Costa, Ann. Sc. Nat. 2nd series, torn. xvi. p. 271, 

 1841, tab. xiii. f. 1, 1a-1d; Grube, Famil. der Annelid, p. 41; 

 Cams, Uandb. der Zoologie, ii. p. 236 ; Quatrefages, Hist. Nat. An- 

 neles, i. p. 411. 

 Hah. Bay of Naples, Costa. 



Genus III. Didtmobeanoiius. 



Didymobranchus, ScAwiarrfa, Neue wirbell. Thiere, 1863; Cams, Handb. 



der Zool. ; Quatrefages, 

 This genus has not apparently been seen by any other observer 

 than Schmarda, who has described two species. It is distin- 

 guished by the absence of caruncle and antennae, by having one 

 row of feet, but having both a dorsal and ventral cirrus and the 

 branchiae pectinated and disposed eacli in two separate fascicles. 



Sp. 1. DiDTMOBEANCHUa CETPTOCEPHALUS. 



Didymobranchus cryptocephalus, Schmarda, Neue wirbell. Thiere, ii. 

 p. 138, tab. xxxiii. f. 262; Quatrefages, Hist. Nat. des Anneles, i. 

 p. 411. 

 Kah. Near Valparaiso, Schmarda. 



Sp. 2. DiDYMOBEANCHXTS MICEOCEPHALUS. 



Didymobranchus microcephalus, Schmarda, Neue wirbell. Thiere, ii. 



139, tab. xxxiii. f. 263 ; Quatrefages, Hist. Nat. Anneles, i. 411. 

 Ilab. Coast of Chili, Schmarda. 



