540 DESCEIPTIONS OF NEW TWO TRILOBITES. 



distinct, surrounding axial furrow shallow but distinct. Occipital furrows 

 shallow. Occipital ring strong, smooth, but having an indistinct trace of a median 

 tubercle, arched, lateral extensions strong. Fixed cheeks large, very mildly con- 

 vex and lower than the glabella. Limb wide, approximately half as wide as the 

 length of the glabella, convex between the front of the glabella and marginal 

 furrow; margin fairly strongly upturned and thickened. Free cheeks unknown. 

 Eye ridges faint and gently arching obliquely to the eye. Eye lobes small and 

 creseentic. Facial sutures anteriorly straight and parallel, posteriorly pass out 

 in front of the genal angle. Thorax consists of thirteen segments, widest at the 

 fourth segment; greatest width equal to its own length and that of the pygidium 

 together. Axis narrow, less wide than one side lobe, tapering very gradually 

 posteriorly, ending with half of its anterior width, convexity moderate. Axial 

 furrows shallow. Side lobes slightly lower at the axial furrows than at the 

 fulcra and flat between these points; gently deflected between fulcra and margin, 

 margins depressed, ends of segments rounded, free, with little, if any, forward 

 direction; medial furrow of each pleura distinct and reaching just to the marginal 

 end. Pygidium small, subsemielliptic, posterior margin rather straight, mildly 

 tumid. In the axis there are four ring-s ; three pleurae in each side lobe. There 

 is evidence that on each ring of the axis medially there was a tubercle; similarly 

 each pleura of the side lobes was ornamented at its fulcrum. 



Dimensions: Total length, 23.4 mm., greatest width, 14 mm., length of head, 

 7.8 mm., of thorax, 12.5, of tail, 3.1 mm. Except for the missing free cheeks 

 this fossil is the finest specimen of a lower Palaeozoic trQobite yet discovered 

 in Australia. If the subgenus Liostracus were likely to be retained, the charac- 

 teristics of our specimen should place it here rather than with Ptyelioparia. 

 The head-shield of our species resembles that of P. stracheyi Reed. The thorax 

 and pygidium are rather closely similar to those of this species, but the ends 

 of the pleurae of the former are rounded and horizontal while those of the latter 

 are pointed and recurved. 



The species is dedicated to Mr. A. L. Merrotsky, the discoverer, in whose 

 possession the original still is. The. above description was made from a cast, 

 presented to the Australian Museum, Sydney (No. L. 1344). 



Locality and horizon. — East of Alroy Downs, Barkly Tableland, N.W. 

 Queensland. Probably of Cambrian age. 



EXPLANATION OP PLATE LIV. 



Cordania gardneri, n.sp. 



Fig. 1. A nearly complete head-shield. It shows most of its characteristic 



features belonging to that part of the fossil, except the eyes, (x 2 approx.) 



Coll. Mitchell. 

 Fig. 2. A pygidium, viewed from above, (x 3.) 



Pig. 3. Pygidium viewed obUquely from behind to show the tuberculation. 

 Pig. 4. A nearly complete specimen. The glabella is broken away and exposes 



the hypostome in situ, (x 2i). Coll. Mitchell. 

 Fig. 5. A side view of the same specimen shown in fig. 4. 

 Fig. 6. Portion of a head which shows the left side very perfectly and the close 



resemblance it bears to the head of a Cyphaspis. 

 Fig. 7. Photo, of pygidium, showing serration of axis. 



Pliillipsia (Griifithides) convexicaudatus Mitchell. 

 Fig. 8- A nearly perfect non-testiferous cast, (x 2J). 

 Figs. 9 and 10. Photos of a squeeze from the cover of the preceding specimen. They 



exhibit the details rather clearly, fx 2). Coll. T. H. Pincombe. 



Ptyelioparia merrotskii, n.sp. 



Figs. 11, 12. Photo, of a plaster cast of the original, (x 2}). Coll. Australian 



Museum, Sydney, N.IS.W. 



