280 AMERICAN JOURNAL 



type of this genus, they must be consolidated, but, pending such 

 an examination, in view of the considerable conchological differ- 

 ences which exist, this would be hardly admissible. The denti- 

 tion and interrupted branchiae separate it definitely from the 

 genus Nacella, although the shells are very similar. It is not 

 probable that any of the species of "jVacg/^a" from the north- 

 west coast are congeneric. 



Type Patina pellucida, Linn., sp. PI. 16, fig. 30. 



Patella jyellucida, Lin., Syst. Nat. xx, 1260. 



Patella Icevis, Penn, Brit. Zool. iv, p. 144, pi. xc, fig. 151. 



Patella ccerulea, Pult., Cat. Dorset., pi. xxiii, f. 6. 



Patella bimaculata, Mont., Test. Brit., p. 482, pi. xiii, f. 8. 



Patina la.'vis, Leach, Moll. Gt. Brit., p. 224, No. 1. 



Patina pellucida, Leach, ib., p. 224, No. 2. 



Patella ca^ruleata, Da Costa, Brit. Conch, p. T, pi. 1, f. 5, 6. 



Patella elongata, + elliptica, Flem., Ency. Edin. pi. 204, fig. 



2, 3. 

 Patella cornea, Pot. and Mich., Gal. Donai. Moll. p. 525, pi. 



xxxvii, f. 5, 6. 

 Patella intorta, Pennant, + P. ?nzMor, Wallace, fide Jeff'reys. 

 JTelcion pellucidum, Jeffreys, Brit. Conch, iii, p. 242. 



Soft parts. Foot oval, sole yellowish white edged with a 

 narrow brown line, body cream color with a tinge of brown in 

 front ; mantle often bordered with a grey or lead colored line, 

 fringed with fine white cirri, alternately long and short ; gills 

 whitish, interrupted in front of the adductor ; mouth minutely 

 puckered, head small ; tentacles slender, long ; eyes small, on 

 their outer bases. Habitat upon the stalks and fronds of large 

 fuci, British and North European Seas. 



I have not been able to obtain specimens of the soft parts, 

 and have quoted from Jeffreys and others; the dentition is from 

 Loven. 



Although the shells are very similar, the animal differs 

 strongly from that of Nacella. Clark makes the statement that 

 the orifices of the anal and genital papillae are below the right 

 tentacle on the side of the neck, not on the side of the body as 

 in other species, but this requires confirmation, and is probably 

 an error. There are a number of other species which will pro- 

 bably find a place in this genus ; they are now usually termed 

 Nacella. 



