PROCTONOTID^. 57 



Habitat : On Corallines and Laminarice in shallow water, 

 sometimes in company with the last ; pretty generally diffused 

 on our coasts, but not common. 



Family IV. PROCTONO'TID^, Alder and 

 Hancock. 



Mantle more or less distinct : dorsal tentacles non-retractile, 

 without sheaths : oral tentacles small or none : branchial pro- 

 cesses fusiform, linear, arranged round the mantle and in front 

 of the head: vent generally dorsal: mouth armed with corne- 

 ous jaws. 



Genus I. PROCTONO'TUS [^q, Alder and Hancock. 



Body depressed : dorsal tentacles simple, linear, without 

 uniting crest : oral tentacles originating in a veil : branchial 

 processes fusiform, arranged along a ridge of the mantle on the 

 sides of the back and in front of the head : vent posterior, 

 dorsal : mouth with corneous jaws and a broad denticulated 

 odontophore. 



This genus was characterized in the * Annals of Natural 

 History ' for March 1844 under the name of Venilia ; but the 

 authors, subsequently finding that name preoccupied, changed 

 it in the following; number of the same work to Froctonotus. 



Proctonotus mucroni'ferus^ Alder and Hancock, 



Venilia mucronifera, A. & H. in Ann. N. H. 1st ser. xviii. p. 161. Proc- 

 tonotus mucro7iiferus, Brit. Nud. Moll. fam. 3, pi. 42. 



Body ovate-oblong, depressed, fawncoloured, marbled with 

 brown : dorsal tentacles simple, corrugated, fawncoloured : 

 oral tentacles short, originating in a subbilobed veil : branchial 

 processes inflated, ovate or inversely pear-shaped, tapering to 

 a blunt point above, and strongly mucronated over the surface ; 



[ * From the vent being dorsal.] 



D 5 



