274 



but I did not see a single specimen of 7. athinsoni, so, 

 probably, it is a rare form in northern Tasmania. It is 

 probable tlie same applies to King Island, wbich I have not 

 visited. 



Distribution. — I have pointed out in a previous paper 

 that the shell under review occurs in the mouth of the Der- 

 went, in Tasmania, but does not occur in the D'Entrecasteaux 

 Channel. From the Derwent it extends round the eastern 

 and northern coasts of that island; is common in Victoria, 

 from Port Phillip, westward, reaching its western limit in Gulf 

 St. Vincent, in South Australia. In Frederick Henry Bay 

 and Port Arthur, in southern Tasmania, it appears to attain 

 its highest development. I have specimens measuring 36 x 17 

 mm., and Mr. May has still larger ones, but the Victorian 

 and South Australian open coast specimens are also often very 

 fine; but in Gulf St. Vincent, although very common, it shows 

 a distinct falling off in size, but maintaining the same char- 

 acteristics as those from the localities previously named — of 

 course the sculpture in these smaller specimens is proportion- 

 ally less strong. 



Ischnochiton crispus, Reeve (Con. Con., Reeve, pi. xix., 

 fig. 120). The following is Reeve's description: — "The 

 Crisped Chiton (Cuming Museum). — Shell elongately ovate, 

 terminal valves, and lateral areas of the rest finely, decussately, 

 crenulately crisped, central areas smooth, or under the lense 

 very minutely reticulated; olive-green thickly painted with 

 dots of a dark colour, ligament minutely, granulosely coria- 

 ceous, obscurely tesselated. Habitat, Australia. Note. — 

 Allied to C. longicymha, but distinguished from that species 

 by the minute decussated character of the sculpture of the 

 lateral areas. May, 1847." 



I propose to recognize in the New South Wales form 

 Reeve's Ischnochiton crispus, which will be a sub-species of 

 Ischnochiton lineolatus, Blainville. Reeve's figures are very 

 good, and there can be no doubt as to the shell. It is similar 

 in its remarkable range of marking and colouration to the 

 southern form, and, if anything, in some specimens even more 

 delicate in its colours. The sculpture is less coarse than is 

 the normal character of that shell. Reeve's comment on the 

 sculpture of the lateral areas being fairly appropriate, but the 

 character of the scales on the girdle easily distinguishes it 

 under a good binocular microscope, mag. 28 to 65 times; 

 the flutes or ribs on the scales of' the Sydney shell are narrower 

 and the grooves correspondingly less deep, and although the 

 scales are considerably larger than is the case with /. atkinsoni, 

 Ire. and May, they are barely as large as those of I. lineolatus, 



