BY R. ETHEKIDGE, JUNR., AND JOHN MITCHELL. 487 



CaLYMENE DUNI, Sp.liOV. 



(Plate xxiv., fig. 8: and Plate xxvii., fig. 12). 



Obs. — Two specimens of Calymene, among those which have 

 come under review, exhibit one or two features so different from 

 those noticed in the foregoing species, that we are compelled to 

 treat them separately. They belong to the C. blumembachii-tyipe 

 in possessing the five divisions in the pleurte of the tail, and the 

 last being parallel with the axial groove. The axis has eight 

 annulations, is very strongly arched, and the bases of annulation 

 are not tuberculated, the arching is apparently highest at the 

 second and third rings and diminishes gradually posteriorly, the 

 last ring is subtended by a subsemicircular piece succeeded by a 

 less prominent area between it and the margin; the axial grooves 

 are wide and shallow, and very distinctly separate the pleurse 

 from the axis; the pleural divisions are traversed by very wide 

 and moderately deep medial furrows, quite unlike the furrows of 

 any species of Calymeiie known to us, reaching apparently to the 

 border; the body of each pleura, formed by the junction of the 

 divisions, is strong and rounded, without median sutures, though 

 such sutures are quite noticeable between the thoracic somites, 

 which would indicate a very complete anchylosis of the parts. 

 This feature, again, is singular, as far as we are aware. One of 

 the specimens shows, near the distal end of the third and fourth 

 ridges, a bifurcation, or, more correctly, free ends. 



The pygidia above described represent very large individuals. 

 The larger one has a length of 36 mm., and the other 27 mm.; 

 one of the axial rings of the former has a length of 8 mm., which 

 would give, for the thorax, a total length of 104 mm.; and, 

 assuming the cephalon to have been half as long again as the 

 pygidium, or 54 mm., the total length of the specimen, to which 

 the larger pygidium belonged, must have had a length of 194 

 mm., equal to 7| inches, far exceeding the length of any Calyniene 

 known to us. 



We have no hesitation in giving specific rank to this singular 

 form. Named after Mr. W. S. Dun, Palaeontologist, Department 

 of Mines, New South Wales. 



Loc. and Hot — Goodradigbee River, near the Wee Jasper 



