508 SILURIAN TRILOBITES OP NEW SOUTH WALKS, vi., 



Fig. 4. — Cephalon without the free cheeks, showing a rather thin and 



straight frontal border, 

 Fig.o. — Cephalon with the test preserved, exhibiting the granulation ; 



(reduced). 

 Fig. 6. — Portion of a cephalon showing the four lateral glabella-furrows; 



(reduced). 

 Fig. 7. — Pj'gidium showing the normal form, the strong arching of tiie 



anterior axial rings, the arching imargination centrally' in the pos- 

 terior border, and granulation. 



Calymene diuri E. & M. 

 Fig.8. — A verj' large pygidium with a few somites attached, showing well 



the features referred to in the text. 



Calymene aui^tra/ls E. & M. 

 Fig. 9. — A perfect specimen contorted and flattened, showing subquadrate 



or subfusiform shape assumed by the pygidium when it has lieen 



depressed by pressure. 



Crotalocephalus silrerdaleim.^ E. & AI. 

 Fig. 10. — Fragmentary pygidium of a Crotalocfphalu.s, assumed to belong 



to tills species. 



(Photos by C. Glutton. ) 



Plate XXV. 



Crota/ocepha/us nlrerdalen-^i-^ E. & M. 



Fig. 1. — A fairlj' good cephalon and thorax of a specimen, three-fourths 



mature, exhibiting, on the right, genal spine and general features 



of those parts. (Coll. Mitchell). 



Fig.2. — Portion of a cephalon of a mature individual, which probably had 



a length of 10 cm. (Coll. Mitchell). 

 Fig. 3. — A well-preserved, perfect cephalon, except for the absence of the 

 free cheeks. (Coll. Mitchell). 



Crotalocephalns .scn/pfn-^ E. & M. 

 Fig. 4, — Almost complete pj'gidium. Probably the one figured by Jenkins. 



(Coll. Sydnej"^ Universitj')- 

 Fig.o. — Four somites of a tliorax exhibiting the rugged sculpturing, the 

 stronglj' arched axial rings, and some of the pleural spines verj- 

 clearly. (Coll. Mitchell). 

 Fig.fj. — An imperfect pygidium showing one perfect pleural spine. 

 Figs. 7, 8. — Imperfect cephalons, assumed to belong to the same species as 

 represented bj^ Figs. 4, 5, and 0. (Coll. Mitchell). 

 C/'Ota/ocepha/uH dlrerdahnM>< E. & M. 

 Fig.9. — A squeeze from the cover of Fig. 1, showing the ornamentaticjn on 

 the fixed cheeks very plainlj'. (Coll. Mitchell). 

 (Photos by C. Clutton). 



