504 ON THE IDENTITY OP BRONTEUS PARTSCHI, DE KONINCK. 



and width of the pygidium varies to some extent. The relative 

 length of thorax to pygidium runs about 2:3. Four specimens 

 complete enough to take measurements gave thorax to pygidium 

 9:14, 10:15, 11:15, and 14:20 in sixteenths of an inch, which in 

 each case approaches the ratio above given. The ratio between 

 the length of cephalic shield and thorax is much more variable. 

 The measurements of three specimens gave 13:17, 15:18 and 20:28, 

 as the ratios in thirty-seconds of an inch, the difference being 

 greatest in the largest specimen measured. 



Mr. Jenkins assigns eleven thoracic segments to his species, but 

 we cannot perceive more than the normal number found in this 

 genus, viz., ten. He also desci'ibes three in the axis of the pygi- 

 dium but our best preserved tails possess certainly seven. 



Loc. and Horizons. — Bowning Creek, in the Lower Trilobite 

 Bed* of the Bowning series (? Wenlock), associated with Bronteus 

 longesjnnifex, Mitchell, Encrimtrus Mitchelli, Foerste, Acidaspis 

 Verneuili, Barr., and Sphcerexochtis rnirus, Beyr. The Hume beds 

 (Jenkins), are identical with the Bowning series, but Mr. Jenkins 

 places his Yass beds below the Hume beds or Bowning series. 

 From both of these beds Mr. Jenkins collected our species 

 [Hatton's Corner in the Hume beds.] We are disposed to rank 

 the Yass beds with the lower portion of the Bowning series 

 embracing at least the Lower Trilobite bed, because the fossils of 

 the two localities seem to agree closely. 



EXPLANATION OF PLATE. 

 (All figures nat. size, except otherwise indicated.) 



Fig. L — Pygidium and portion of thorax of a fairly large specimen, rather 



narrow tailed. 

 Fig. 2. — Cephalic shield of a large specimen, with free cheeks missing. 

 Fig. 3. — Pygidium from a well preserved, large and wide specimen. 

 Fig. 4.— Free Cheek. 



Fig. 5. — Free Cheek ( x 3), showing ornamentation and facets of eye. 

 Fig. 6. — Free Cheek (mould) x 2, showing ornamentation more distinctly. 

 Fig. 7. — ilestored outline, drawn to agree in proportions with our largest 



pygidium. 



♦Mitchell, Proc. Australasian Assoc. Adv. ^ci. for 1888 [1889], 1. p. 294. 



