Neiv or Little-known Victorian Fossils. 77 



species also in the arcuate border of the lateral margins, and its 

 sharp cardinal extremities. The tigure of the same species given 

 by Hall and Clarke is more extreme, being short, and transversely 

 elongate, with produced and sub-cylindrical extremities^ 



Occurrence. — In a hardened mudstone crowded with casts and 

 decorticated valves of brachipods and other shells, north of 

 Lilydale. Presented by Rev. A. W. Cresswell, M.A. [U17]. 



Horizon. — Silurian (Yeringian). 



Chonetes cresswelli, sp. nov. (Plate XII., Fig. 7). 



Specific characters. — Shell semicircular, hinge line straight, 

 beaks only very slightly projecting ; cardinal extremities obtusely 

 angular. Pedicle valve with a well-marked median fold. Radii 

 sharp, more numerous than in the preceding species, averaging 

 about 56 ut the margin. Shell-surlace marked with one or two 

 faint concentric lines, which do not interrupt tlie continuity of 

 the radii. Eight or more hollow .spines set nearly perpendicular 

 to the cardinal line on the pedicle valve. 



Measurements. 

 An average specimen : — Length - - 9 mm. 

 Width - - 15 „ 



Observations. — The general characters of this and the preced- 

 ing species are somewhat similar, the chief differences lying in the 

 altogether stouter build of shell and fewer radii in Chonetes 

 robusta. The shell in C. cresswelli is usually more elongate 

 transversely, but is variable in this respect. The faint concentric 

 roarkings on the valves of the latter form is another distinguish- 

 ing character. 



In the number of the radii the above species is nearly compar- 

 able with Chonetes australis, McCoy-', from the Middle Devonian 

 of Buchan and Lucknow, Gippsland, but there is no mesial sulcus 

 in the pedicle valve of that species ; the valve is also longer in 

 proportion and the spines are shorter and stouter. 



Occurrence. — This species is found, like the preceding, in the 

 indurated mudstones north of Lilydale associated with Orthis, 



1 Chonetes aciUiradiata, Hall sp., Hall and Clarke, Palaeontology of New York, Palaeozoic 

 Brachiopuda, vol. iv., pt. 1., pi. xvi., fig. 8. 



i Prodr. Pal. Vict., Decade iv., 1870, p. 17, pi. xxxv., figs. 3-5 



