74 GASTROPODA. [Aspidobranchia. 



Subsp. corticata, Hutton, 1880. Plate 5, fig. 17. 



Acmrea corticata, Hutton, M.N.Z.M., 89. A. lacunosa. Reeve : Hutton, 

 T.N.Z.I., xvi, 215; Pilsbry, Man. Conch. (1). xiii, 52, pi. 37, f. 7-11, 

 not of Reeve. A. Stella, subsp. corticata, Hutt. : Suter, P. Mai. S., 

 vii, 325, pi. 27, f. 38-41. 



Shell oval, conoidal, ribbed. There are 14 to 22 rounded, roughened 

 radiate ribs, a few of them short, crossed by incremental ridges. Colour 

 white, nearly always obscured by a layer of Nulliporites. Apex a 

 little in front of the middle, obtuse ; slopes straight ; margin denti- 

 culate. Inside bluish-white, spatula white or brown, sometimes 

 faintly radiately streaked with black ; margin with a black border 

 or dark-brown spots. 



Length, 14 mm. ; breadth, 13 mm. ; 

 height, 9 mm. (type). Length, 13 mm. ; 

 breadth, 9-5 mm. ; height, 5 mm. (speci- 

 men figured). 



Dentition. Hutton, T.N.Z.I., xv, 127, 

 pi. 15, f. L; P. Mai. S., vii, pi. 27, f. 41. 



Type in the Canterbury Museum, Christ- 

 church. 



Hob. The type is from Dunedin ; North TEETH OP RADULA. 



and South Islands ; Chatham Islands. 



Remark. This subspecies is distinguished from the species by 

 the usually smaller size, and the disappearance of the 7 primary, 

 stronger ribs. The margin is not laciniate, and the ribs are more 

 numerous and equal. 



Subsp. pseudocorticata, Iredale, 1908. 



Acmcea pseudocorticata, Iredale, T.N.Z.I., xl, 1907 (1908). 379. 



Shell small, conical, elongate-oval, sides almost parallel, closely 

 ribbed, greenish, with brownish markings between the ribs, margin 

 almost entire. The sculpture consists of about 17 ribs in the young 

 shell up to 30 in the older shell, due to divarication. Apex situated 

 at about the anterior third to subcentral ; almost always eroded, 

 so that the sculpture is only distinct on the lower half of the older 

 shells. Margin entire or feebly denticulate ; very irregular in some 

 specimens, due to their station. The coloration of the outside is con- 

 stantly greenish, the interstices between the ribs brownish. The 

 spatula is distinctly marked, of a pinkish colour ; below is a darker 

 shade of pink ; the margin is white, marked with bluish-black lines 

 corresponding to the interstices between the ribs. This coloration 

 is almost constant ; in some the spatula is whitish or yellowish-white 

 or rarely spotted with black. 



Measurements of a fair specimen 1 are : Length, 13 mm. ; breadth,, 

 9 mm. ; height, 6 mm. (Iredale.) 



