102 HORN EXPEDITION — PALEONTOLOGY. 



Loc. — This species is restricted to the quartzites immediately underlying the 

 fossiliferous limestones at north of Tenipe Vale and at Finke Gorge. 



Actinoceras tatei, Eth., fils., sp. (Plate I., Figs 2^, -lb.) 



Orfhoceras, sp. iiid., Etheridge, tils (ii.), p. 10, t. 1, tig. 4. 



Orthocenu latei, id. (iv.), p. 7. 



Obs. — A vertical section of the shell shows that the siphuncle is moderately 

 swollen between the septa. This structure further separates the species from 

 Ortlwceras saturni, Barr., O. elevatum, Hall, and O. exceiitrkum, Sowei-by, to 

 which it hears a certain external resemblance. The position of the siphuncle is, 

 however, not actually central, as stated by the author of the species. The 

 largest portion obtained lias a maximum diameter of two inches, and indicates a 

 distal extension of sixteen inches. 



Loc. — This shell occurs in great profusion in limestone near camp on Laurie's 

 Creek and to the north of Tempe Vale, also at Tenape Downs, Petermann Creek, 

 Mereenie Blutf", and Chandler Range. 



Trochoceras recticostatum, sp. nov. (Plate I., Figs 5^-5^.) 



Sp. char. — Shell planorbiform with close (though not embracing) whorls. 

 Septa simple, with a slight transverse curvature, about 2 '5 mm. apart at the 

 outer circumference of the penultimate whorl. Section of last whorl elliptic ; 

 sipi)uncle external. Tlu; ornamentation is obliterated by weathering, except on 

 the back of the last whorl, where it consists of slightly elevated, narrow, straight 

 cost;e, sep.) rated by shallow interspaces of about one millemetre wide. Test and 

 body-chamber unknown. 



Obs. — From the slow increase of the close whorls this shell may be regarded 

 as an immature Trochoceras rather than Gyroceras, though the asymmetry of its 

 spire is not apparent. It recalls T. speciosum, Barrande, but the costte are more 

 numerous and not retrovert on the back. 



Loc. — Tn limestone, near camp on Laurie's Creek — a unique example. 



Class Gastropoda. 



Eunema larapinta, sp. nov. (Plate I., Fig. 6.) 



Sp. char. — Shell imperforate, pyramidal ; whorls three (without apex) of 

 somewhat rapid increase, usually rather broadly and bluntly but occasionally 



