80 GASTROPODA. [Aspidobranchia. 



so doing we are dealing with a well-described and figured species 

 which undoubtedly belongs to the New Zealand fauna. There is no 

 absolute proof that our species is identical with the very similar shell 

 from Tasmania and Australia. Species of the Patellidce have usually 

 a very limited range of distribution. 



2. Helcioniscus denticulatus, Martyn, 1784. Plate 7, fig. 10. 



Patella denticulata, Mart., Univ. Conch., ii, f. 65 ; Hutton, M.N.Z.M., 109. 

 Patinella denticulata, Mart. : Hutton, P.L.S. N.S.W., ix, 375. Hel- 

 cioniscus denticulatus, Mart., Man. Conch. (1), xiii, 138, pi. 21, f. 49, 

 50 ; pi. 68, f. 23, 24. Patella imbricata, Reeve, Conch. Icon., f. 95, not 

 of Linne. P. Reevei, Hutton, M.N.Z.M., 108. Patinella Reevei, Hutton, 

 P.L.S. N.S.W., ix, 376. Helcioniscus denticulatus, Mart. : Suter, P. 

 Mai. S., vi, 346. Patella margaritaria, Chemn. : Martens, Crit. List, 36, 

 not of Chemnitz. 



Shell solid, oval elevated. The sculpture consists of 22 to 30 prin- 

 cipal radiate ribs, and some smaller interstial riblets, all of which are 

 closely scale-granose ; this character, however, is often lost in old 

 shells through the dissolving action of the water. Apex more or less 

 anterior, usually at the anterior fourth. Colour varies from light grey 

 with brown ribs to dark brown. Interior bluish, central area well 

 defined, orange-brown ; muscle-scar sometimes raised, bluish-white ; 

 space between central area and margin bluish-white, with dark-brown 

 bands corresponding to the ribs ; interspaces dotted with yellow 

 spots ; margin with dark -brown triangular spots ; highly iridescent. 



Length, 55 mm. ; breadth, 43 mm. ; height, 24 mm. Length, 

 45 mm. ; breadth, 37 mm. ; height, 15 mm. 



Dentition. The inner lateral tooth has a simple long cusp, and the 

 outer lateral has one denticle at the outer edge. 



Hob. Cook Strait ; East Cape, Hutton also mentions Dunedin 

 and the Chatham Islands. 



Remarks. Brought to England by Captain Cook. This species is 

 very local, but plentiful where it occurs. 



3. Helcioniscus ornatus, Dillwyn, 1817. Plate 7, fig. 11. 



Patella ornata, Dillw., Descript. Cat. Rec. Shells, ii, 1029. Helcioniscus 

 ornatus, Dillw., Man. Conch. (1), xiii, 137, pi. 19, f. 39, 40 ; pi. 68, f. 14-19 : 

 Suter, P. Mai. S., vi, 351. Patella nodosa. H. & J., Ann. Sci. Nat. (2), 

 xvi, 191. P. denticulata, Mart. : E. A. Smith, Ereb. & Ter., Zool, ii, 

 Moll., 4, pi. 1, f. 26; Hutton, P.L.S. N.S.W., ix, 375, not of Martyn. 

 P. margaritaria, Chemn. : Reeve, Conch. Icon., f. 74. 



Shell solid, oval or oblong, low conical. Sculpture consisting of 

 larger radiating coarsely nodular ribs, about 11 in number, with a 

 somewhat smaller rib between each pair of larger ones, the intervals 

 radiately striated ; growth-striae fine, often quite distinctly cutting 

 the radial strise. The larger ribs are light, the intermediate ribs 



