340 GEOLOGT AND PETROLOGY OP THE GREAT SERPENTINE BELT OF X.S.W., 



other the Ijeak Ls more proniineiit and separated from the ears l)y a marked 

 flexure. Its margin also is elliptical rather than quadrate. The length of the 

 ioriu from beak to margin is from 30 to 35 millimetres; the breadth is 45. 



According to De Koninck (30) who first recorded this form in New South 

 Wales, it ranges throughout the whole of the Carboniferous System. In Scotland 

 it is found from the Upper Limestone Series to the base of the Calciferous Sand- 

 stone (31) . In England and Ireland the range is from the zone Za to that of Di. 



Orthls (Bhipidomella) australis (McCoy). (Plate six., fig. 9.). 



Orthis australis, McCoy, Ann. Mag. Nat. Hist., xx., 1849, p. -234, t. 13, f. 4-4A; 

 Rhipidomella australis, Dun, Rec. Geol. Sur. N.S.W., vii., 1902, p. 81, t. 

 21, f. 10-11, and Bibhography there cited. 



The specimens obtained by Mrs. Scott from the south-east of Babbinhuon, are 

 all such as show the external form only, and therefore difficult to assign to either 

 Orthis miehelini or Orthis australis. The known abundance of the latter, and im- 

 jirobability of the occurrence of the former may be taken as deciding the nomen- 

 clature of these specimens. The size is normal or rather small. Breadth, 21 mm., 

 length, 19, and depth or thickness, 5 mm. Less well developed specimens were 

 collected by Benson four miles east of Currabubula, and by CuUen from Somerton. 



Rhynchonella pleurodon (Phillips). 



Terebratula pleurodon, Phillips. lUus. Geol. York , ii., 1830, p. 222, t. 12, f. 25, 30; 

 Bhynchonella {Puijnax) pleurodon, Dun, Rec. Geol. Surv. N.S.W., vii., 

 1902, p. 18. t. 23, f. 10, 11 and Bibliography. 



This form is represented by specimens Nos. 4385, 4434, 4435, in the collection 

 of the Geological Survey, obtained by CuUen from the Parish of Moorowarra, 

 south of Somerton. These have not been critically examined by us. The species, 

 however, has been determined critically in specimens from Clarencetowu occurring 

 in the Burindi rocks, and is also abundant in the Upper Devonian rocks of Mt. 

 Lamhie and "S'alwal. In Scotland it is known in the Calciferous Sandstone and 

 Lower Limestone Series (31) . 



Rhynchonella (?) sp. index. (Plate xix., fig. 13.) 



A single specimen of an indeterminate form which may be related to this 

 genus has been obtained by Mrs. Scott from the .south-east of Babbinboon. Its 

 length and breadth are about 8 millimetres, and it is ornamented by fourteen 

 strongly-marked radiating ribs. The evidence is insufficient to justif\ our assign- 

 ing this to any known species. 



DiELASMA .sACCUiiUiM (Martin) var. h.vstata (Sowerby). (Plate xix., fig. 12.) 



Terebratula liaslata, J. Sowerby. Min. t'onch., 1824, t. 440, f. 2, 3; Dielasmii sac- 

 culum var. liaslata, Dun., Rec. Geol. Surv. N.S.W., vii.. 1902, p. 83, t. 21, 

 f. 13, and Bibliograpliy cited. 



Numerous examples of this form have been obtained by Mrs. Scott from the 

 south-east of Babbinboon. The dimensions show considei-able variation, the fol- 

 lowing measurements Ijeing representative : — • 



a b c tl 



Length (beak to margin) 20 27 18 9 



Breadth 10 10 14 10 



Thickness 8 — 8 — 



