379 



According to Mr. E. 0. Thiele there are two limestones,, 

 a "pale grey," containing Brachiopods and Girvanella and 

 a "dark bluish-grey," with the crustacean fragments in ques- 

 tion/ 30 ) "sections cut in all directions," says Mr. Chapman. 

 This fragmentary condition of such remains is not uncommon 

 in our Cambrian rocks, particularly in the Kimberley lime- 

 stones and the friable sandstone of Caroline Creek. 



19.15. — In the "Bulletin of the Northern Territory" for 

 December, 1915, are photo-prints of a Trilobite cast, found 

 by Mr. Surveyor Merrotsy on the Barkly Tableland, eight 

 miles east of Alroy Downs; "the rock matrix is a cherty 

 replacement of limestone, "( 31 -) which accords well with the 

 lithological composition of the Ord River bed. This cast is 

 described in the present communication as Ptychoparia 

 alroiensis , and is the most perfect example of this group of 

 animals . yet found in the Australian Cambrian. Mr. Mer- 

 rotsy's discovery is one of great importance, indicating a 

 further extension eastwards in all probability of the series 

 yielding Olenellvs forresti, 0. browni, Agnostus elkedraensis, 

 etc. 



1918. — Some years ago Mr. H. Y. L. Brown forwarded 

 to me pieces of a grey-white limestone from Clinton, on the 

 east side of Yorke Peninsula, at the head of Gulf St. Vincent. 

 Throughout these limestone fragments are the broken-up 

 remains of a Trilobite, which appears to me to be quite dif- 

 ferent from any one yet found in the Yorke Peninsula. 



III. Observations on the Species. 



Genus Agnostus, Brongniart, 1822 



(Hist. Nat. Crust. Foss., 1822, p. 38). 



Agnostus elkedraensis, Eth. fit. 



A. elkedraensis, Eth., fil. : Off. Contributions Pal. S. Austr., 

 No. 13 (S. Austr. Pari. Papers), 1902, p. 3, pi. ii., figs. 1-4. 



Obs. — In addition to the comparsions already made in 

 the above communication, attention may be called to another 

 Cambrian species — A . montis\, Matthew. ( 32 > I have examined 

 the specimens of this pretty Australian form, and cannot dis- 

 tinguish more than one thoracic segment. This absence of the 

 second can hardly be a matter of development, as the normal 

 number are acquired at a very early stage in the meta- 

 morphosis of the genus. 



< 3 0) Thiele: Proc. Roy. Soc. Vict., xxi. (n.s.), pt. i., 1908. 

 ( 3 i)Anon. : Bull. N. Territory, No. 14, 1915, pis. ii. and iii. 

 ( 3 2) Matthew: Trans. Rov. Soc. Canada, v. (2), 1899, p. 48, 

 pi. i., f. 6. 



