56 Proceedings of the Royal Society of Victoria 



I have submitted these fossils to a most careful examination 

 and long considei'ation, and having exhausted all means of 

 comparison at my disposal, the conclusion is forced on me that 

 they represent to us in Australia, at least, an undescribed genus. 

 Neither do the specimens seem absolutely in accord with any 

 of the American or European genera, descriptions of which are 

 available. Under these circumstances, T propose describing the 

 Heathcote Trilobites under the new name of Dinesiis* and the 

 trivial appelation of ida, with the view of recording their place 

 of occurrence. The combined generic and specific description 

 will be followed by some observations on the alliances of the new 

 genus. 



DiNESUS IDA, geii. et sp. nov. 



Chars. — Cephalic shield sub-semicircular; frontal border raised, 

 nearly straight centrally, separated from the glabella and iixed 

 cheeks by a frontal furrow. Glabella oblong, or long oval, 

 slightly convex, straight-sided, and rounded in front; no furrows; 

 basal circumscribed lobes pyriform, separated completely from 

 the glabella by deep grooves ; axial grooves very wide and deep, 

 bifurcating near the fore-end of the glabella, one branch pro- 

 ceeding round the latter and joining the frontal groove, the other 

 round the fixed cheeks on each side, leaving between them and 

 the frontal groove somewhat triangular circumscribed lobes. 

 Fixed cheeks more or less elongately triangular, wider behind, 

 very gently convex ; eye-lobes small, slightly projecting ; ocular 

 ridges extending obliquely across the fixed cheeks to the anterior 

 corners of the glabella; facial sutures convex in front of the 

 eyes, curving inwards and cutting the frontal border in line with 

 the outer edge of the fore circumscribed lobes, and, posterior to 

 the eye-lobes convex also, dividing the posterior border of the 

 head-shield near the position of the genal angles. Neck ring 

 strong, convex, and devoid of a spine ; neck furrow wide and 

 flattened, the lateral furrows similar. Surface, although devoid 

 of the test, frosted with minute granules. 



Pygidium sub-semicircular to obtusely triangular, truncate 

 behind ; axis flattened, of five segments ; pleurie flattened, of a 



* 7/ vr7(T0S an is'and, and 8t in allusion to the two basal circumscribed lobes. 



