314 Chapman and Gabriel : 



differences being the usually heavy and thickened structure of the 

 shell in Gorhula ephamilla , along with the greater attenuation of its 

 anterior. 



Distribution.— Bore 1, 2US-210 feet. Bore 3, 226 feet. Bore 

 4, 163-170 feet. Bore 5, 165-169 feet; 162-163 feet; 175-189 feet. 

 Bore 6, 114-150 feet; 150-154 feet; 154-168 feet; 158-161 feet. 

 Bore 7, 142 feet 3 inches-155 feet. Bore 8, 165-180 feet; 180-199 

 feet; 199-204 feet; 204-210 feet; 210-219 feet. Bore 9, 254-256 

 feet; 263-273 feet; 315-325 feet. Bore 10, 220 feet; 254-296 feet; 

 310-320 feet. Bore 11, 199,209 feet. 



Class SCAPHOPODA. 



Fam. DENTALIIDAE. 



Genus DENTALIUM, Linne. 



Dkntalium aratum, Tate. 



Dentalium aratum, Tate, 1887, Trans. Roy. Soc. S. Austr., 

 vol. ix. p. 192, pi. XX. fig. 8, Idem, ibid., 1889, vol. 

 ixiii. p. 265. 



A critical examination of the recent related forms of the above 

 genus has resulted in the following conclusions : — The Australian 

 Dentaliidae form a large group, the characters of which show 

 a great amount of variation. D. aratum is no exception, and the 

 species most likely to be confused with that form are the living D. 

 robustwn, Biazier,' D. intercdi.atnm, Gould,'- and D. fvancisense, 

 Verco.3 D. robustum can be separated by the absence of longi- 

 tudinal striae. A constant feature of the costation in D. inter- 

 calatum is in the ribs becoming distinctly rounded in later growth. 

 In the case of D. franclsense we agree with Verco, who remarks, " I 

 am inclined to think that even this species is but an extreme variant 

 of the D. iiitercaldtum, Gould." 



Distribnfiof I. —Bore 1. 215-244 feet. Bore 3. 226 feet. 



1. Proc. Liiiii. Soc. N.S. Wales, vol. ii., 1877, p. 56. Hedle.v Rec. Austr. Miis., vol. iv., No. 3. 

 1901, p. 128, pi. xvii., fijf. 32. 



2. Proc. Bost. Soc. Nat. HiHt., vol. vii., ISfiO, p. 106. SowvrUy in Reeve's Icon. I'onch, vol 

 xviii., 1872, pi. vii., fi;,'. 40. 



3. Tran^:. Ro.v. Soc. S. Austr., vol. xxxv., 1911, p. 2(i7, pi. xxvi., fiffs- 1, 1". 



