BY JOHN MITCHELL. 48? 



The tuberculation, too, on this border is similar in the three 

 species. Dimensionally, this species agrees closely with Br. 

 strzeleckii, judging from the dimensions given by Reed,"^ so also 

 does it in part in the character of the ornamentation, but in 

 part in this respect, it differs very widely, as the description 

 shows. 



The chief differences between our species and Br. strzeleckii 

 are — 1. The character of the ornamentation. 2. The more conical 

 shape of the glabella in ours, and the absence of the large longi- 

 tudinally placed tubercles on this part. 3. The more acutely 

 rounded cephalon, particularly at the front. 4. The eyes are 

 situated closer to the posterior border, and perhaps to the 

 glabella. 5. The lateral extensions of the neck-ring are narrow 

 and prominent. Without doubt, the two forms are closely 

 related. 



Since writing the above, I have found, on some of the Queens- 

 land specimens from Rockhampton and Mt. Morgan districts, 

 several pygidia and a portion (cheek) of a cephalic shield, which 

 belong to the genus Brachymetopus. One of these pygidia, 

 which is fairly well preserved, I am assuming to be specifically 

 identical with the cephalon above described. Its description is 

 as follows. 



Pygidium semicircular, only mildly convex, strongly tuber- 

 culate. Axis moderately prominent, contracting gradually pos- 

 teriorly, ending short of the border bluntly, with less than half 

 its anterior width: it bears five longitudinal rows of tubercles, 

 the individuals of the middle row being much larger than those 

 in the rows on each side of it. There are at least twelve or 

 thirteen rings in the axis, and a central tubercle on ten of these 

 can be clearly seen; this applies also in the case of each row 

 immediately adjacent to the central one. Axial furrows deep. 

 Side-lobes consist of six (? seven) pairs of segments, the ridges of 

 which are very prominent, and bear several relatively large 

 tubercles and some of smaller size: each of the posterior pair 

 merely consists of a tubercle, and each ridge of the anterior pairs 

 bears several tubercles varying much in size, the larger being 



'■' Geol. .^Ja.^, X.S., Dec. iv., Vol. x.. IIMKS. pp. llKMUfJ. 



