678 SILURIAN TRILOBITES OF NEW SOUTH WALES, V., 



Plate Iv. 

 Encrinurus mitchelli, Foerste. 



Fig.l.— A nearly perfect testiferous specimen, the test being absent from 

 the glabella and pygidial axis only. The submucronate termina- 

 tion of the pygidium is well shown. Bowning. Coll. Mitchell. 



Fig.2. — Sliows the almost perfect hypostome in position. Bowning. Coll. 

 Mitchell. 



Fig. 3. — Another testiferous specimen, exhibiting the much greater size of 

 the last annulation of the thoracic axis than that of the first of the 

 pygidial axis, and which is very characteristic in this species; also 

 continuity of six of the annulations of the pygidial axis anteriorly, 

 whereas, in non-testiferous specimens, three only are usually so. 

 Bowning. Coll. Mitchell. 



Fig. 15. — A left free cheek, to show the eye and the non-inward trend of 

 the axial groove. Bowning. Coll. Mitchell. 



Encrinurus silverdalensis, E. db M. 



Fig. 4. — An imperfect tail showing eight or nine tubercles on the central 

 area. Bowning. Coll. Mitchell. 



Fig. 9. — Hypostome showing lobation, etc. Silverdale. Coll. Mitchell. 

 Encrinurus bowningensis, Foerste. 



Fig. 5. — A portion of a cephalon, to show the prominent eye. Bowning. 

 Coll. Mitchell. 



Fig. 6. — Left free clieek ( X 2), to show how the axial furrow passes out- 

 wardly into the side-furrow of the cheek, and obliquely inwardly 

 across the inner lobes. [The artist has here intensified the obliquity]. 

 Bowning. Coll. Mitchell. 



Fig. 12. — A right free cheek, to show the same features as Fig. 6 more 

 correctly. Bowning. Coll. Mitchell. 



Encrinurus etheridgki, Mitchell. 



Fig. 7.- A portion of a cephalon [vide PI. liv. , fig. 13, ante']. 



Fig.8. — Portion of a cephalon ( x2), showing identity of features with the 

 above Fig. 7. Bowning. Coll. Mitchell. 



Encrinurus «p.(?) undet. 



Fig. 13. — Pygidium with continuous axial annulations, and twelve pairs 

 of pleural segments. Found associated with E. dunt^^oonensis. This 

 and the following (Fig. 14) are distinct from all pygidia known to 

 us, and if not belonging to E. duntroonensis, represent one, if not 

 two, new species. Duntroon. Coll. Mitchell. 

 Encrinurus «/>.(?), iindet. 



Fit^. 14. — ^Pygidium witli axial annulations continuous, and ten pairs of 

 pleural segments. (See remarks above, Fig. 13). Duntroon. Coll. 

 Mitchell. 



