244 AMERICAN JOURNAL 



margin. Foot oval, thin, sides smooth ; head rosy, short, broad 

 and semicircular ; muzzle very short, frill produced into two lap- 

 pets, as in the last species. Tentacles rather long, slender, 

 pointed. Gill very long, drab, extensile and contractile, narroAv 

 and situated on the left side of the head, base a little forward of 

 the junction of the neck and hood and springing from the un- 

 der surface of the mantle, pointing from left to right across the 

 neck and composed of a thin membrane bearing a series of la- 

 mellag above, and another somewhat larger series below, as in 

 most Acmgeids. Anal and infra-anal papillae as in the last, renal 

 not detected. Formula 



0( T— T— l7l^=i^T]0. 



The specimens from which the above notes were taken were 

 dredged by- Dr. Stimpson near Oban, Scotland. It ranges from 

 Iceland to the Azores (Jeffreys.) It has not the slightest resem- 

 blance whatever to Acmcea asmi of Middendorf, as suggested by 

 Jeffreys (1. c.) 



The shell has been well described by Forbes and Hanlej^ and 

 Jeffreys, op. cit. 



The statement of Clark in regard to the uidification of the ova, 

 is too widely different from the habits of the other species to be 

 taken without further confirmation ; it is probably a misappre- 

 hension caused by the entanglement of some loose ova in the 

 mucus of the foot. 



AcM^A INSESSA, Hinds. PI. 14, fig. 3. 



Patella insessa, Hds., An. Nat. Hist, x, p. 82, pi. vi, f. 3. 



Nacella incessa, Cpr., Sup. Kep. Br. As. 1863, p. G50. 



Soft parts slitty green, upper edge of mantle dark brown. 

 I\Iantle and sides of foot smooth ; tentacles cylindrical, stout, 

 moderately long ; eyes black, small on the upper posterior ten- 

 tacle-bases, foot smooth, subovate ; gill small, broad, triangular ; 

 muzzle frilled, disk granulose or nearly smooth, frill .produced 

 at each outer lower corner into two bluntly rounded lappets. 

 Radula narrow, cusps reddish brown, rather more slender than 



in the last species. Formula 



0(1— 1— il^^^P-^T)0. The speci- 

 men which affords the above notes was obtained from a Lamina- 

 ria frond at Monterey. Range from Sitka (rare) to Monterey 

 (common) and San Diego (scarce.) 



In the young and perfect condition this shell has some very 

 peculiar brilliant white marks on the apex which appear to con- 

 sist, in a shell '2 of an inch long, of a band in front of the apex, 

 one just behind it, and a V-shaped mark still more posterior. 

 These are, however, confined to the first and thinnest layer of the 



