542 R. B. Neivton — CJionetes Pratti in W. AusU'alia. 



III. — On the Occurrence of Chonetes Pratti, Davidson, in the 



Carboniferous Eocks op Western Australia. 



By R. BuLLEN Newton, F.G.S., 



of the British Museum (Natural History). 



[Read at the British Association, Edinburgh Meeting, 1892.] 



(PLATE XIV.) 



THE Government of Western Australia, througli their Geologist, 

 Harry Page Wooilward, Esq., F.G.S., has recently presented to 

 the British Museum an important series of Palaeozoic invertebrate 

 fossils which have been collected from various localities during the 

 progress of the geological survey of that colony. 



Since their arrival in this country the majority of the specimens have 

 been figured and described in the Geological Magazine for 1890, 

 by Mr. A. H. Foord, Dr. G. J. Hinde, and Prof. H. A. Nicholson. 



Among the Brachiopoda from the Irwin River District are three 

 well-preserved valves of a Chonetes, consisting of two dorsals and 

 one ventral, which have not yet received identification from the 

 authors referred to, as they came in a second consignment, and after 

 the description of the first series had been published. These valves 

 belong to one species, though to different specimens ; the ventral 

 being deeply convex, possessing a prominent central depression, 

 and internally showing well-defined muscular scars, whilst the 

 dorsals retain in singular clearness the reniform vascular im- 

 pressions in addition to the usual muscular markings. 



Desirous of being able to refer these specimens to some described 

 species, it was necessary to consult the unique collection of Brachio- 

 poda formed by the la,te Dr. Thomas Davidson, now contained in 

 the British Museum, and which at the present time is undergoing 

 a detailed arrangement. There my attention was drawn to the 

 figured example of a form called Chonetes Pratti, which Davidson 

 had described as long ago as 1869, in the *' Geologist," and which 

 apparently has never since been referred to either by the author 

 himself or by any other specialist of the Brachiopoda. This type 

 consists of a dorsal and ventral valve belonging to the same animal, 

 and its comparison with the Western Australian specimens has 

 resulted in the fact that in every essential character, both minera- 

 logical and structural, it is identically the same, a point of much 

 interest when it is remembered that the Davidson specimen up 

 to this time has been without locality or horizon. I'he author's 

 description of this species is included in the Explanation of the 

 Plates attached to his essay " On the Families Strophomenidse and 

 Productidge," published in the "Geologist" for 1859 (pi. 4, figa. 

 9-12, p. 116), and is here reproduced, the words in square brackets 

 being used to connect the meaning : — 



Chonetes Pratti. — This beautiful specimen (from the collection of Mr. Pratt) 

 is here given as an illustration of the genus, on account of the admirable preservation 

 of its valves. The specimen is silicitied ' and the valves can be as easily separated 



1 This statement requires correction, as on submitting the figured examples to the 

 test of Hydrochloric acid their structure is fouud to be calcareous. My colleague, 

 Mr. Thomas Davies, F.G.S., has also examined the fractured edge of one of the 

 valves, and he identities the cleavage planes as belonging to Carbonate of Lime. 



