114 Proceedings of the Royal Society of Victoria. 



■more than two and a-half times the height. Upper and lower 

 edges straight or slightly undulate, and divergent towai'ds the 

 posterior extremity. Ends gently rounded ; lower edge of valve 

 apparently notched or fimbriate in some specimens. Length of 

 figured example, 12 ram.; height, 4.5 mm. 



Observations. — The valves of S. tetragona as they occur in the 

 Victorian rock-specimen (a pale crumpled shale), are somewhat 

 -distorted, but the general outline can be distinctly made out in 

 one or two better preserved examples. Its nearest ally seems 

 to be S. minor, ^ from the Lower Oi'dovician of Arenig and 

 Portmadoc. 



Localitv and Horizon. — Collected by the Geological Survey of 

 Victoria B. 26. [196.] Lower Ordovician. 



Genus Rhinopterocaris, gen. nov. 



Generic characters. — Carapace bivalved, long ovate, shaped 

 somewliat like the wing of a dipterous insect. Dorsal border 

 gently convex, ventral more strongly curved ; well-rounded 

 posteriorly, tapering more acutely towards the anterior extremity, 

 the anterior portion of the carapace sometimes exhibiting traces 

 of tht)racic or rostral structures. The caudal extremity having 

 a short, sharply pointed telson, with vestiges of a sharp stylet. 



•Carapace smooth, hut having a few strong lateral folds on the 

 ventral margin, and one on the dorsal margin. Masticatory 

 apparatus like that of Dithyrocaris, but having the highest cusps 

 in the middle of the ridge. An elongate pyriform pit is seen in 

 the area immediately below the dorsal border at the anterior end, 

 which seems to be comparable with the stalk-eye socket of the 



■recent Nebalia, to which the palfeozoic phyllocarids appear to be 



tmost nearly allied. 



Rhinoptepocapis maccoyi, Etlieridge, HI, sp. 

 (PI. XVIIL, Figs. 9, ? 16, 17). 



Lingulocaris maccoyi., R. Etlieridge, fil., 1892, Records Geol. 

 Surv. IST. S. "VVale-s, vol. iii., pt. 1, pp. 5-8, pl. iv. 



1 Jones and Woodward, 1891, Rep. Brit. Assoc, p. 424, figs. 1-17 ; Ibidem, 189-2, Men. 

 Brit. Pal. Phyllopoda Pal. Soc), p. 86, pl. xiv., fi<;s. 7-9. 



