118 Proceedings of the Royal Society of Victoria. 



Class BRACHIOPODA. 



Genus Sip]ionotreta., de Verneuil, 1845. 



Siphonotreta maccoyi, sp. nov. (PI. XVIIL, Figs. 12-14).. 



Description. — Valves sub-circular, front margin broadly 

 rounded, sides irregularly rounded; surface of valves slightly 

 convex and acuminate towards the foramen. Dorsal valve 

 smaller and broader than the peduncle valve. Foramen small. 

 Surface of valves ornamented with a series of fine, numerous and^ 

 equidistant concentric striations, which are slightly imbricate, 

 and bearing vestiges of blunt spines at distant intervals. Lengtb 

 generally equal to the breadth. The specimens vary considerably 

 in size, and examples of intermediate dimensions occur; those 

 from the Lower Ordoviciau are usually smaller than those of 

 the Upper Ordovician. Limits of length measurement of specimens 

 in the National Museum, 4 to 10 mm. 



This species is easily separable from S. micula,^ to which it 

 bears most resemblance, by having a much larger number of 

 concentric strige, which are also finer; the latter form usually 

 exhibit three or four concentric lineations, which are very 

 strong and distinct. 



In S. maccoyi the foramen is small and generally obscure, but 

 can be traced by the position of the median fissure, seen in the 

 more or less crushed examples, resulting from the fracture of the 

 thin shell over the pedicle tube. Many of the valves have been 

 distorted by pressure, laterally, longitudinally, or obliquely. 



Observations. — In 1867 Prof. M'Coy noted the occurrence of 

 Siphonotreta in Victoria, and referred to the fossils in the 

 following words'- : — 



"As a general rule, the Graptolite slates in every part of the 

 world contain no other fossils. I, many years ago, discovered in 

 Wales, near Builth, the only shell I ever heard of in Graptolite 

 slates (the Siphonotreta viicula., M'Coy), and I was greatly 

 surprised to recognise it also in Victoria in the Deep Creek 

 section." 



Since the above date this fossil has often been quoted as S. 



1 Brit. Pal. Fosa., 1852, p. 188, pi. IH., fi<j.3. Also Davidson, Mon. Brit. Sil. Brach. 

 (Pal. Soc), 1866, p. 76, pi. viii., figs. 2-6. 



2 Ann. Mag. Nat. Hist., ser. 3, vol. xx., 1867, p. 201. 



