Helcioniscus.] GASTROPODA. 83 



iridescent, with the brown radiating ribs shining through the pearly 

 layer ; central area milk-white to greyish-olive. 



My largest specimen, from Tauranga, has the following dimen- 

 sions : Length, 60 mm. ; breadth, 50 mm. ; height, 18 mm. 



The dentition is unknown. 



Hab. East coast of both Islands ; not common. 



Subsp. Earlii, Reeve, 1855. Plate 7, fig. 16. 



Patella Earlii, Reeve, Conch. Icon., f. 71. Xacella Earlii, Reeve: Hutton, 

 C.M.M., 45. Patinella Earlii, Reeve : Hutton, P.L.S. N.S.W., ix, 376. 

 Helcioniscus Earlii, Reeve, Man. Conch. (1), xiii, 140, pi. 21, f. 51, 52. 

 H. radians, Grnel., subsp. Earlii, Reeve : Suter, P. Mai. S., vi, 348. 

 Patella flexuosa, Hutton, C.M.M., 45, not of Quoy and Gaimard. 



Distinguished from the species by the rounded-oval form, the 

 convexly raised front, the broad blood-red blotches, and the milk- 

 white central area. This is a very distinct and easily recognised 

 subspecies. The altitude is generally not greater than in the species, 

 but the breadth is much greater in proportion to the length. 



Length, 60 mm. ; breadth, 50 mm. ; height, 16 mm. (specimen 

 from Tauranga). Length, 50 mm. ; breadth, 42 mm. ; height, 16 mm. 

 Length, 47 mm. ; breadth, 39 mm. ; height, 11 mm. (both from Te 

 Onepoto). 



Dentition the same as in the species. 



Type in the British Museum. 



Hab. Along the east coast of both Islands : Tauranga ; Te One- 

 poto and Sunnier, near Lyttelton ; Akaroa ; Tirnaru ; Preservation 

 Inlet. Chatham Islands. 



Subsp. affinis, Reeve, 1855. Plate 7, fig. 17. 



Patella affinis, Reeve, Conoh. Icon., f. 108. Helcioniscus affinis, Reeve, 

 Man. Conch. (1), xiii, 140, pi. 69, f. 32, 33. H. radians, Gmel., subsp. 

 affinis, Reeve: Suter, P. Mai. S., vi, 349. Nacella Earlii. Reeve: 

 Hutton, C.M.M., 45 (according to specimens in the Dominion Museum), 

 non Reeve. Acmcea chathamensis, Pilsbry, Man. Conch. (1), xiii, 1891, 

 56, pi. 35, f. 43-46 ; Suter, P. Mai. S., vii, 1907, 326. 



Distinguished from the species by its smaller size, the elongated- 

 oval form, the numerous simple, smooth, slightly waved radiate ridges 

 and stride. The typical, close, divaricating colour-pattern is not 

 always present ; sometimes there are only brown radiate bands visible, 

 which, especially in Chatham Island examples, coalesce, forming 

 broad dark-brown or black patches. The concentric striation is mostly 

 very distinct. 



Length, 33 mm. ; breadth, 27 mm. ; height, 7 mm. (specimen 

 from Stonyhurst). Length, 27 mm. ; breadth, 20 mm. ; height, 

 6-5 mm. (specimen from Chatham Islands). 



Dentition the same as in the species. 



