BY THE REV. J. E. TENISON- WOODS, F.G.S., F.L.S. 237 



In the foregoing diagnosis it will be seen that our specimen 

 differs from B. australis in its greater length, in tapering to a point, 

 and the slightly different curvature of the lateral groove. It 

 resembles it in all other particulars, especially in the depression by 

 lateral expansion of the post alveolar region, in the lateral grooves 

 being so sharply cut in the alveolar and post-alveolar region and 

 in the absence of the ventral groove. 



I do not therefore think it advisable to erect it into a new 

 species, but should it prove new I propose for it the name of 

 B. oxys. (PL xiii., tigs. 1, 2 and 3.) 



This species belongs evidently to the division Hastati of M. 

 d'Orbigny as Mr. Moore has pointed out in the case of the specimen 

 from Wollumbilla. In this group the guard is elongated and 

 provided with lateral grooves for a portion of the length, but 

 always with a long ventral groove, which is wanting in the Aus- 

 tralian species. The typical species of the group is B. hastatus, 

 Blainville, which is found in all the middle Oolitic beds from the 

 Kellaways rock to Upper Oxfordian. Other members of the same 

 group have been found in the Oolites of France, England, Russia, 

 and the province of Cutch in India. Other forms of the Hastati 

 are found in the Lower Cretaceous, so that the group is consi- 

 dered to belong to the middle and upper mesozoic rocks. 



NEW SPECIES. 



Trigonia mesembria, sp. nov. PI. xn., figs. 1, 2 and 3. T. t. oblongo- 

 ovali, postice producta, tumida, crassa, umbonibus paidlum ante- 

 rioribus, pro7ninulis, haud curvatis ; margine superiore concavo, 

 elongato, margine posteriore curvato, sed postice truncato; Antice 

 tumide producta, rotundata ; s^dco posteriore lato, conspicuo, 

 minime profundo, m/i,rginibus valde divergentibus a natibus ad 

 marginem ; costis ti-ansversalibus, haud prominulis, costulis 

 aliquando inter calantibus antice parum undulosis sidco posteriore 

 evanescentibus ; carina Icevi, sulcis tribus Icttiusculis munita, 

 lunula longa Icevi ovata, 2 sulcis longis latis, sculpta, basin 

 versus striata ; dentibus cardinalibus crassis conspicuis marginibus 

 super ioribus bi-sulcatis, sulcis later alibus IS, crebris, concinnis. 



