275 



Blainville, in shells of a corresponding size. I have 

 collected it at Bulli and Port Jackson, and have been fur- 

 nished with additional material from that place by Mr. Hull,, 

 and from Caloundra, in Queensland, by Dr. John Shirley. 

 The largest specimen I have in my collection measures 

 30 X 13 mm. 



Ischnochiton atkinsoni, Ire. and May (Proc. Mai. Soc., 

 pts. ii. and iii., Nov., 1916, p. 110). The size of the type is 

 given as 8 X 4"5 mm., and senile shell as 13 x 7 mm., and the 

 range given in their paper as northern Tasmania. Since then 

 Mr. W. L. May has taken it in Little Norfolk Bay, southern 

 Tasmania, and he and I took it in considerable numbers in 

 the D'Entrecasteaux Channel. This extension of its range 

 is somewhat interesting, especially the latter, as there Z. lineo- 

 latus, Blainville, was entirely absent. The sculpture is most 

 consistent, the coarse granules being always in evidence in 

 the dorsal area as well as on other portions of the shell. 

 While there is some divergence in colour from dark-brown 

 through buff to dirty- white, this divergence is within very 

 restricted limits. 



Juvenile shells of this species are in the D'Entreeasteaux 

 Cliannel living with large numbers of juvenile Heterozona 

 sub-viridis, Ire. and May, described in the same paper. If 

 anything, /. atkinsoni prefers deeper water. Except by 

 means of a good lense it is difficult to separate juveniles of 

 these two species, as the characteristic girdle scales of suh- 

 viridis only put in an appearance at a later age, but the dorsal 

 area, in the latter, is smooth. 



Ischnochiton atkinsoni lincolnensis, n. sp. 



Living with I. lineolatus, Blainville (auct. I. crispus), 

 in Victoria at San Eemo, and in South Australia at 

 Encounter Bay, Cape Jervis, and Gulf St. Vincent, is a small- 

 scaled Ischnochiton which was bulked with the large-scaled 

 species, I. lineolatus, Blainville, until Ire. and May described 

 from Tasmania I. atkinsoni. I have examined a very large 

 series starting from Wilson Promontory, in Victoria, through 

 the localities previously named; from Port Lincoln, where I 

 collected a large series in January, 1917; from St. Francis 

 Island, collected by Dr. Torr; from Venus Bay, collected by 

 the writer, in February, 1910; and a few from Esperance 

 Bay, in Western Australia, collected by Dr. Torr, which place 

 seems the limit of its extension westward. From Port Lin- 

 coln, westward, I. lineolatus, Blainville, seems entirely absent, 

 and its place is taken by the species now under review. 



The following is a comparison with the Tasmanian shell : — 

 The sculpture of 7. lincolnensis in the pleural areas is similar 



