Victorian Fossils, Part XII. 307 



Dorypyge, a tA^pical Ciunhiian genus, to which the former seems 

 quite closely allied : and latterly Mr. C. D. Walcott has also 

 remarked^ on the relationship, stating- that Dinesiis of Eth., jnr. 

 (the pygidimn of which is now referred by Prof. J. W. Gregory 

 to y of (isa pitas):' appears to he more nearly related to 

 Dori/pi/f/f, Dames, than to Damesella or DorypygeIJa, Walcott." 

 The genus Dory pyyt- is found throughout the Cambrian, and, in 

 China, also occurs in a bed above the Ac/nostus zone. 



With regard to the affinities of the Liau-tung fauna, which 

 shows Some points in common with that of the Mt. Wellington 

 limestones. Dames considers it to correspond with the Scan- 

 dinavian Andrarum Limestone, and to the lowest division of 

 the Potsdam Sandstone in America.^ 



General Chapacters of the Limestones. 



The tiilobite-bearing limestone is dark bluish grey in colour, 

 and partially crystalline. The samples collected by Mr. E. 0. 

 Thiele are crowded with the remains of these Crustacea, chiefly 

 parts of the cranidia, with an occasional pygidium of the larger 

 forms ; whilst the heads and tails of Agnostus .are found scat- 

 tered pretty freely over the fractured surfaces of the rock. 

 Several fragments of the thoracic pleurae, presumiably of 

 Ptychoparia and Crepicephalus, can be distinguished, but no 

 connected pieces were obtained. Evidently the membrane con- 

 necting the elements of the thoracic region was excessively 

 delicate and easily separated. 



In thin sections under the microscope the trilobite limestone 

 is seen to be practically caloitic. haying a coarsely crystalline 

 structure. (See PI. LX., Fig. 25.) Tbe nmtrix contains innumer- 

 able sections of the trilobite carapaces cut in all directions. 

 The latter are usually encrusted on both upper and undci- 

 surfaces by a thin layer of a black carl^onaceous substance of a 

 granular texture, commonly seen in trilobites that are at all 

 well preserved. The thickness of these fragments of trilobite 



1 Proc. U.S. Nat. Mus., vol. xxix., 1906, p. 35. 



2 Proc. Roy. Soc. Vict, vol. xv. (n.s.), pt. ii, 1903, p. 15.5, pi. xxvi., flys. 11, 12a, lib, 13. 



3 Dames, in Richthofen's "China," vol. iv., 1883, v>. 28. See also H. Woodward, Geol. 

 JIag., 1905, pp. 21-2, 213. 



Ca 



