230 Mr. F. M'Coy on the Fossil Botany and Zoology 



form, in the midst of the cheeks (? smooth) ; eye-lines un- 

 known. Surface strongly granulated ; one tubercle on each 

 side of the anterior end of the glabella, the marginal row and 

 a circle round each eye being larger than the rest. Body-seg- 

 ments unknown. Pygidium nearly resembling the cephalo- 

 thorax in size and form, rather more pointed, strongly trilobed, 

 and with a thickened prominent margin ; axal lobe about as 

 wide as the lateral lobes, of about seventeen narrow segments ; 

 lateral segments about seven, divided from their origin, each 

 terminating in a large tubercle at the margin. 

 The minute Trilobites for which I propose the present genus 

 are very distinct in habit from those of other genera, and as two 

 or three species are now known, it seems desirable to place them 

 together under one name. They are the smallest perfect Trilobites 

 known, from two to three lines being the greatest width they have 

 been seen to attain. The Phillipsia Maccoyi of Capt. Portlock's 

 Geol. Report on Londonderry, &c. certainly belongs to this genus, 

 and is at first sight difficult to distinguish specifically from the 

 Australian species. The Irish species alluded to was collected by 

 the writer from the lower carboniferous limestone of Kildare, and 

 sent to Capt. Portlock for his monograph of Irish Trilobites, 

 under the impression that it formed the type of a new genus 

 and species, but probably from there being but one specimen it 

 was placed provisionally by that author in his genus Phillipsia, 

 from which it differs in its small, short glabella, smooth eyes, 

 want of cephalothoracic furrows, &c. Having now examined 

 numerous specimens of the Australian species, there can be no 

 longer any doubt of the distinctness of the group from Phillipsia 

 from the characters of the cephalothorax, and the pygidium is 

 still more distinct. From those materials I have therefore drawn 

 up the above characters, which it is believed will distinguish them 

 easily from the other generic types. From the general similarity 

 in the structure of the pygidium, I am inclined to refer the fossil 

 which I have named Phillipsia (?) discors (Synopsis of the Garb. 

 Limestone Foss. of Ireland, pi. 4. fig. 7. p. 161) to the same 

 genus. This is also a very small Trilobite, the length of the 

 pygidium being only three lines ; and although referring it pro- 

 visionally to Phillipsia, I suggested in the above work that it 

 should when better known form the type of a distinct genus, 

 which however it was not possible to frame until now. I have 

 dedicated the present species to Count Strzelecki, whose fine 

 work on the physical features of New South Wales and Van 

 Diemen's Land has so materially advanced our knowledge of that 

 country, and who has recorded the existence of minute Trilobites 

 (undetermined) in the limestone of Yass Plains, which probably 

 belong to this group if not to this species. 



