206 



since they occur only in these two instances, among several 

 hundred Dentalium shells. These are often bored, but gener- 

 ally only in one or two holes and in other parts of the shell. 

 However, it would be perilous to construct another species to 

 include these two examples, which in all other respects 

 resemble the rest under this name. My longest individual 

 measures 20 mm. by 2*25 mm. Hedley's type is 8 mm. by 

 1 mm., and probably immature. 



Dentalium bednalli, Pilsbry and Sharp. 



Dentalium bednalli, Pilsbry and Sharp, Tryon, Man. Conch., 

 1897-8, vol. xvii., p. 248, pi. xxxix., figs. 1, 2, and 3. Type 

 locality — Gulf St. Vincent, South Australia. (P)i>. octogonum, 

 Lam., Angas, Proc. Zool. Soc, 1878, p. 868; Adcoek, Handlist 

 Aquatic Moll., S.A., 1893, p. 10. 



Dredged in 15-22 fathoms in Gulf St. Vincent, 59 speci- 

 mens with 7 ribs posteriorly and a varying number anteriorly ; 

 after the previous 7 -angled varieties have been picked out. 



Dentalium octopleuron, n. var. 



This shell is like D. bednalli, Sharp and Pilsbry, except 

 that it has 8 ribs at the posterior end instead of 7. In 4 

 specimens the 8 costse run throughout the shell, which may 

 measure 20 mm. in length. But in all the others riblets 

 arise ; it may be in only one or in two, or up to all the 

 intercostal spaces. These riblets may number as many as 4 

 in a space ; they may equal in size the primary ribs, if they 

 are few, or they may remain small, especially if numerous. 



Dredged in 15 to 22 fathoms in Gulf St. Vincent, 88 in 

 good condition. This variety is the most common in our 

 shallower waters, and this would be the form found by Angas 

 on Henley Beach and named by him D. octagonum, Proc. 

 Zool. Soc, 1878, p. 868. 



Type in Dr. Verco's collection. 



Dentalium robustum. Brazier. 



Dentalium robustum, Brazier, Proc. Linn. Soc, N.S.W., 

 1877, vol. ii., p. 56. Type locality — Katow, New Guinea, 8 

 fathoms, sandy mud and coral (Chevert Exped.) ; Pilsbry and 

 Sharp, Tryon, Man. Conch., 1897-8, vol. xvii., p. 12; Hedley, 

 Records Aust. Mus., 1901, vol. iv., No. 3, p. 128, pi. xvii., fig. 32; 

 Bossevain, Scaphopoda, Siboga Exped., 1906, p. 29. 



Dredged in 15 to 22 fathoms in Gulf St. Vincent, 16 in 

 good condition. These, like the type, have 9 ribs throughout. 

 Besides these 28 other specimens from the same locality have 

 9 ribs posteriorly and more than 9 anteriorly. 



