98 NOTE ON SOME TRILOBITES NEW TO AUSTRALIA, 



The eyes in our specimen are prominent and much brought 

 forwards compared with those in other allied species. What is 

 missing is the fi-ontal margin, including the two triangular grooves, 

 by which it is connected with the ocular ridges and the facial 

 suture. This frontal margin, in some, is adorned with series of 

 tubercles (A. minuta, A. Leonhardi, A. Roemeri), while in others 

 it is smooth {A. Hoernesi). Barrande says that the head of A. 

 Dormitzeri is similar to that of A. Leonhardi, but his (figure 22, 

 pi. 38), of the former does not show tuberculations at the frontal 

 margin. 



Fui'thei", the head of our fossil exhibits a more rounded outline 

 than any of the other species considered. I will explain it 

 simply. Let us draw a straight line parallel to the axis of the 

 body and passing by the origin of one of the genal spines. In 

 Acidaspis Dufrenoyi, Barr., (PI. 38, fig. 25), this line will form an 

 angle with the external border of the movable cheek, which is 

 nearly straight giving to the head the shape of a triangle. In 

 some of the species mentioned such as A. Hoernesi, A. Dormitzeri, 

 the angle will be smaller; in A. Roemeri still smaller; in A. 

 minuta this angle will be reduced to nothing, as the line will be 

 tangential to the head-border ; and lastly in our fossil, and still 

 more so in A. Verneuili, Barr., (PL 38, fig. 5), the border will be 

 cut by the parallel line. That border is adorned by a regular line 

 of tubercles, each of which gives rise to a very fine spine, the 

 impression of which has been left on the stone. The genal spines 

 are bent nearly in a direction parallel to the outline of the body. 



The body has nine rings ; each pleura is terminated by a spine 

 progressively incurved from the first to the last, which is nearly 

 parallel to the axis. 



The pygidium is I'ather difl&cult to understand in so small a 

 specimen ; it is much adorned with tubercles and shows distinctly 

 eight spines, but whether the principals are the second or the third 

 in order, ic is not easy to decide. 



In resume there are two strong characters in our fossil in favour 

 of making it a difierent species from those represented in Barrande, 



