r,v JOHN' MiTCi[i';i.i.. 545 



The longtli ami ilt'plh oi the latter speciiueu arc practically iduntioal with the 

 similar measurements of one of the two large specimens of the local forms given 

 ahove. In the case of the former species sometimes the length is greater than the 

 width and sometiiiieis the reverse; in the latter, the length is always greater than 

 or equal to the width, as far as nuiy he determined from the specimens at present 

 available. In (uitline and external features, adult specimens of the two shells 

 are not sejjarable, and if the specific determination of the local shells were to be 

 made after a comparison with the adult specimens of M. pleheia Sow., I would 

 without hesitation place it with that species, but the youthful forms of the British 

 (Plymouth) species, as represented in figs. 7-8 (loc. cit.) are unlike any of the 

 youthful specimens of our form. Further the umbo and beak of the pedicle 

 valve of the local form seem more prominent than are* these pai'ts of the British 

 species. These slight differences may hardly justify the separation of the two. 



The relationship between M. tennesseensis Hall and Clarke, ajid ours is also 

 close. The largest specimens figured by Hall and Clarke (Nat. Hist. N.Y., Pal. 

 18()4, Vol. iii., Brach. ii., PI. xlii., figs. 1-0) have length 15.6 mm., width 14.75, 

 depth 9.4 mm. 



In figure 5 thi' length and width are 15. (J mms. for each dimension. By 

 referring to the dimensions given above for local shells, the close agreement of 

 some of them will be plain. Therefore, from dimensional evidence, these two 

 might be placed together; but M. tenmsseemis, .iudging from the figures, was 

 smaller, and possessed a more conspicuous sulcus in the pedicle valve than the 

 New South AVales type. The valve margins, lateral and anterior, of the latter 

 are more sinuous than they are in the former. 



After full consideration it seems to me that the Australian type might be 

 placed with either the British M. pleheia or tlie American M. tennesseensis Hall 

 and Clarke, but appears to be nearer the former than the latter; therefore it is 

 placed with that species, though the immature specimens of our form do not 

 appear to exactly agree with the similar British ones. 



As far as I am aware this brachiopod has not previously been recorded from 

 this State. In England it occurs plentifully in rocks of middle Devonian age. 



The specimens here described and figured were collected from a mass of lime- 

 stone within an extrusion of trachyte at the base of Bulga Hill, Tulcumbah, near 

 Carroll, on the property of Mr. John Tydd. The geological age is, doubtless, 

 middle Devonian. A brachiopod which, outwardly, bears a strong resemblance 

 to the shells above described, was collected by the writer from Cave Flat, near 

 the junction of the Murrunibidgee and Goodradigbee Rivers, from rocks which 

 are referred to as lower in middle Devonian. 



Family SPIRIFERIDAE. 



Spirifer bowningeksis, n.sp. (Plate xxxi., figs. 21-22.) 



Spec. Chars. — Shell transversely subelliptic, radially strongly ribbed, and 

 finely and densely striated. Pedicle valve strongly convex, possesses ten to twelve 

 folds, sulcus dee]) and very wide anteriorly, umbo prominent, beak pointed, in- 

 curved, and somewhat obscuring the area; folds abutting the sulcus very pro- 

 minent. Brachial valve mildly convex, has ten folds exclusive of the medial one 

 which is prominent, and medially traversed by a shallow wide sinus; beak not 

 conspicuous. Hinge line long, straight, almost as long as the greatest width 



