NOTODELPHYS. 307 



Cetochilus septentkionalis, Goodsir. (Plate XVIII. 

 fig. 2.) — Bright-red and slightly translucent; about a line 

 and a half or two lines long. Antennas very long and 

 slender, of twenty-four joints, the twenty-second and twenty- 

 third joints each furnished with a long seta pointed down- 

 wards and inwards. 



Hab. Firth of Forth. 



Next to Cetochilus Dr. Baird provisionally places the next 

 genus, which he says must form the type of a new family. 



Gen. 168. NOTODELPHYS, Allman. 



One eye. Head and first ring of thorax consolidated. 

 Thorax of four, and abdomen of four segments. Upper an- 

 tennae many-jointed ; lower prehensile. Four pairs of foot- 

 jaws. Ovary, a large sac placed behind the last ring of the 

 thorax, and within the parietes of the body.* 



Notodelphys ascidicola, Allman. (Plate XVIII. fig. 

 3.) — Upper antennae of twelve short joints, each with one 

 or more setae. Abdomen somewhat cylindrical. 



Hab. Belfast Bay, and other Irish harbours: found swim- 

 ming freely in the branchial sac of the Ascidia communis, 



* Hence the name, from vwtos, back, and SeXcpvs, matrix. 



