298 Frederick Cha])')nan, : l 



Pygidium short, subtriani^ular, with rounded sides and a , 



bluntly acuminate extremity. 



Dimensions. — Length of tyj)e specimen, 17 mm. ; greatest ; 



width, 11 mm. ; length of cephalon, 4.75 mm. ; length of thorax, 

 7 mm. ; length of pygidium, 5.25 mm. 



Observations. — A species described by A. F, Foerstel, under i 



the name of Encrinurus mitclielli, bears some relationship to ■ 



the present form. It was described from specimens sent by Mr. 

 J. Mitchell from the silurian of Bowning, New South Wales. 

 When on a recent visit to Melbourne Mr. Mitchell saw the pre- ] 



sent specimens and suggested that they were the same as E. | 



mitchelli. Since then I have carefully examined a large series j 



of specimens in the National Museum collection from the Yarra ! 



Improvement Works and elsewhere near Melbourne, and have \ 



drawn the conclusion that they are distinct from the Bowning 

 species although bearing strong affinities to them. The speci- 

 mens here selected as the holotype of E. (C.) sj^ryi was that 

 labelled by Sir F. McCoy shortly before his decease, and that \ 



name is here retained. The differential characters between E. 

 mitchelli and E. (C.) sjjryi are these, viz., in the former the 

 carapace is longer ; the axis is broader ; the glabellar furrows ! 



are almost obsolete ; the pygidium has nearly straight instead 

 of curved sides ; and the extremity is more acuminate, as in a 

 typical Encrinurus. 



Occurrence. — In grey mudstone and shale from the Yarra 

 Improvement Works, South Yarra. Also in various excavations • 



in Melbourne. This is the commonest trilobite in the Melbourne 

 bed-rock. Silurian (melbournian). Type presented by Mr. F. P. i 



Spry in November, 1897. I 



I 



Fam. Calymexidab. ] 



Crenus Homalonotus, Koenig. 1 



•I 



Homalonotus vomer, sp. nov. (PL LXIL, Figs. 2, 3, PI. LXIII., j 



Figs.-1, 2). j 



Description. — This species, having an elongate, convex, trian- I 



gular head, with a lobed glabella and non-remote eyes, falls 



1 Bull. Sci. Lab. Denison Univ., vol. iii. 1886, p. 124, pi. xi fi<rs. 2, 3, 20. 



