88 . ISCHNOCHITON. 



There is no certainty in the identification of de Blainville's loiigi- 

 cymba but I have accepted the form recognized under that name by 

 Quoy, as he was the first to figure the species. This identification 

 compels us to regard the New Zealand shell as the type form. Figures 

 58, 60-66 represent New Zealand specimens furnished me by Prof. 

 Hutton and Mr. G. W. Wright. These differ from the Australian 

 form, which I have named Haddoni, in the much less distinct, less 

 regular striation of the girdle scales, the broadly rounded arch of 

 the back, and the short, abruptly terminating posterior tooth of the 

 side insertion plates. 



I. HADDONI Pilsbry, n. sp. PI. 22, figs. 67-73. 



Shell distinctly keeled on the back ; scales of the girdle beauti- 

 fully regular in size and arrangement, and evenly and deeply grooved 

 (fig. 67). Sculpture and color patterns like I. longicymba. 



Interior white, greenish or bluish ; anterior valve with 10, cen- 

 tral 1, posterior valve 12 slits; teeth thin, sharp. Posterior tooth 

 of the intermediate valves long, extending almost to the posterior-lat- 

 eral angle of the valve, and not terminating abruptly (fig. 72). 



Length 27, breadth 12 mill. 



The coloring is even more variable than in the New Zealandic 

 J. longicymba; some specimens are clear, light greenish-buff (fig. 

 71) ; some are brown, speckled all over with olive-black ; some are 

 mainly red, or black, having a wide white dorsal stripe. 



Port Jackson, Australia. 



Chiton longicymba SOWERBY, Conchol. Illustr. f. 67. REEVE, 

 Conch. Icon. t. 24, f. 163a-c. Ischnochiton longicymba CPE., MS., 

 and of HADDON, Challenger Rep. Polyplac. p. 17 (not Ch. 

 longicymba Quoy). 



Having examined extensive suites of specimens of the longi- 

 cymba type of Ischnochitons from New Zealand and Australia, I 

 find myself compelled to separate specifically those from the latter 

 locality, although in general appearance, color and sculpture they 

 certainly resemble the true longicymba. The differences indicated 

 above, and shown in the figures, seem to be remarkably constant, 

 and readily recognized if one takes the trouble to look for them. 

 It must be admitted, however, that to thoroughly examine a small 

 Chiton involves some little trouble ; and therefore we must feel no 

 surprise if the superficial collector and the often no less superficial 

 author, continue to confound species which are really distinct. It 



