ETCHEMINIAN FAUNA OF NEWFOUNDLAND. 195 



a strong fold which is more than two-thirds of the whole length of the 

 shield. The lower and posterior border has a distinct marginal fold. 

 The front border is angulated, but no rostral piece is known. 



tllllt. ARCUATA. PI. III., fig. 6. 



This form is somewhat smaller, is rounded in front, and the shape 

 is more elongate. 



The surface in these little shells is granulated and there are traces 

 of concentric grooving. The largest is about 3|x2 mm., the mutation 

 about 3x1 J mm 



SUMMARY. 



The peculiarities of this fauna as distinguished from the Cambrian 

 are the following : 



1. Great preponderance of the tube worms {Hyolithiihe, etc). 



2. Absence or rarity of trilobites. 



3. Minuteness of the Gasteropods except Capulidse. 



4. Minuteness of the Brachiopods. 



5. Minuteness of the Crustaceans. 



The two special types of the Etcheminian fauna are, among the 

 Hyolithidae OrthotHeca bayonet, and among the Gasteropoda Randomia 

 Aurora. The minuteness of the Lamellibanchs is not peculiar to the 

 Etcheminian as the Cambrian species are not much larger. 



DESCRIPTION OF THE PLATES. 

 Plate I. 



Fig. 1. Obolella c. f. ehromatica, Bill. Ventral valve, mag. \. See 

 p. 189. 



Fig. 2. Kutorgi/na granulata, n. sp. a Ventral valve; — b Dorsal 



valve ; both mag. \; — c Dorsal (?) mould of, (/ Vent. 



ral, hinge seen from behind. Both mag. |. See p. 1S9. 



Fig. 3. Randomia Auroras, n. gen. et sp. a Side view, restored from 

 two examples ; — b Same seen from above ; — c Smaller 

 entire shell. All natural size. See p. 190. 



Fig. 4. Platyceras transversum, n. sp. a Side view ; — b Same seen 

 from above. Mag. ^. See page p. 191. 



Fig. 5. Platyceras radiatum, n. sp. a Side view ; — b Seen from 

 above. Mag. |. See p. 191. 



