44 



No. 1 specimen, measuring 9x6 mm., is similar in 

 method of sculpture to the shells from Marino, in South Aus- 

 tralia, and shows the coarsely pustulose radial ribs in the 

 lateral areas, which is so marked a feature in that form. 



The tail valve, although thickened at its posterior mar- 

 gin, is not as distinctly upturned. 



Nos. 2 and 3 are quite distinct in sculpture; they 

 measure, respectively, 14x9 and 13'5 x 6 mm. The last- 

 named, it will be seen, is long and narrow; quite an unusual 

 form for members of this genus. 



The lateral areas in these two are almost smooth, with 

 the exception of the second valve, which in specimen No. 2 

 gives some evidence of diagonal ribs; in No. 3 a few large 

 nodules are present. 



These two specimens suggested affinities with Torr's 

 Plaxiphora hedleyi, and so I took the earliest opportunity of 

 visiting the Doctor, who, with his usual kindness, allowed me 

 to make careful examination of his types. I find that the 

 shells I have called 2 and 3 are undoubtedly his species, 

 designated under the name Plaxiphora hedleyi (Trans. Roy. 

 Soc. S. Austr., vol. xxxv., 1911, p. 103). I also find that 

 Dr. Torr's Plaxiphora zebra, described in the same paper 

 (p. 106) from a single median valve, is similar in sculpture 

 to my specimen No. 1, and corresponds with the South Aus- 

 tralian shell known as K. matthewsi, Ire. Prior to 1910 

 Australian collectors used to refer to this shell as Plaxiphora 

 cqnspersa, Ad. and Ang. In June of that year Iredale 

 described it under the name of P. matthewsi. 



Seeing that Dr. Torr's paper was read in October, 1911, 

 his P. zebra becomes a synonym of Iredale's shell. Although 

 it is possible that there is only one very variable species in 

 the waters of South Australia and Western Australia, which 

 the finding of these three shells, above described, in the same 

 hole at the same time, rather supports, I prefer for the present 

 to retain Torr's name as hedleyi, as a sub-species of Kopionella 

 matthewsi, Ire., and represented by the forms I have herein 

 described as Nos. 2 and 3, with almost smooth lateral areas. 

 The delicate and remarkable "oar-head spicules," which sug- 

 gested to me the name of the genus, were no doubt removed 

 from Torr's specimen in rough handling in the cleaning. 



The tail valve, as shown in Torr's fig. 2e, is a little mis- 

 leading, the part of that valve behind the mucro is really 

 the thickened edge of the upturned portion; neither is the 

 slight indentation of the girdle behind the mucro indicated 

 in his fig. 2a. 



