272 



A REVIEW OF CHITON CRISPUS, REEVE, (ORDER POLY- 

 PLACOPHORA) AND ITS ALLIES, WITH PROPOSED RECOG- 

 NITION OF Blainville's chiton uneolatus, and 



DESCRIPTION OF THREE NEW SPECIES. 



By Edwin Ashby, F.L.S., M.B.O.U. 



[Eead September 9, 1920.] 



Plates XI. and XII. 



Whilst most Australian workers have been aware that 

 under the name of Ischnochiton cris'pus, Reeve, several inde- 

 termined species have been bulked, no real attempt has been 

 made to separate these forms and define their specific or sub- 

 specific differences to assign their respective habitats. I did 

 a good deal of preliminary work prior to July, 1919, and my 

 thanks are due to Mr. W. L. May, who kindly examined a 

 good deal of my material, and then expressed the opinion that 

 there were four different species living together at Marino, in 

 this State, and usually classed as one. My thanks are also 

 due to Dr. W. G. Torr for material from St. Francis Island 

 and Western Australia; to Mr. A. F. Bassett, Hull, for addi- 

 tional specimens from Port Jackson; and to Dr. John Shirley, 

 for specimens from Caloundra. 



The extreme variability in pattern and colouration and, 

 to a lesser degree, in sculpture, of the group of shells we have 

 hitherto designated as Ischnochiton crispus, Reeve, has made 

 this one of the most tedious investigations I have attempted. 



The use of a good binocular microscope was essential to 

 the task, which has entailed the examination of some thousands 

 of specimens from a great number of localities, extending from 

 Caloundra, in Queensland, to Esperance, in Western Aus- 

 tralia, and from many parts of Tasmania. 



I propose to recognize Chiton lineolatus of Blainville in 

 the large-scaled Ischnochiton of Tasmania, Victoria, and parts 

 of South Australia, and to recognize Ischnochiton crispus of 

 Reeve in the New South Wales shell, classing it as a sub- 

 species of the former. Iredale and May's Ischnochiton atkin- 

 soni, senu stricto, is recognized as confined to Tasmanian 

 waters, in both sculpture and colouration, showing very little 

 variation. Then I define, as a sub-species of this latter, under 

 the name of lincolnensis, Ashby, a form which is more variable 

 and whose range extends from Victoria to Western Australia. 

 A new species with minute scales is described under the name 



