FAUNA OF THE ST. JOHN GEOUP. 43 



fainter and nearer the back of the shell, and the umbonal callus is smaller than in the 

 other two. 



ACROTEETA. Kutorga (1848). 

 AcEOTRETA Baileyi. Matt. ? (PI. XII, fig. Id.) 



'Trans. Roy. Soc. Can.,' Vol. iii, Ft. iv, p. GO, PI.. 5, figs. 13<f, h, c. 



A small species which agrees with this in size and in the form of the dorsal and 

 ventral valves, occurs in the upper part of the Dictyouema shale, in company with the 

 Linnarssonia described above. The internal markings of the dorsal valve are distinctly 

 those of an Acrotreta, and the ventral valve has the conical form, with flattened area, 

 characteristic of the genus. 



Size. — Full-sized samples are about 3| mm. long and 4 mm. wide, but many are 

 much smaller. 



Horizon and Locality. —In a bed of fine grey shale enclosed in the black slates of Div. 

 3 c at Navy Island, St. John Harbour. 



This species differs from A. gemma, Bill., of the LeA'is shale' in its larger size, in the 

 less elevated ventral valve, and in the branching internal mesian ridge of the dorsal 

 valve (though this is not a constant character). 



Gr. Lindstrom records the occurrence of an undescribed Acrotreta in the Ceratopyge 

 limestone of Sweden, which is just above the horizon of this species.- Davidson figures 

 and describes a species (A. Nicliolsoni) similar to this in size and appearance, found in the 

 Llandeilo Group of Dumfriesshire, Scotland.'' 



OBOLUS, Eiclmald. 



M. de Yerneuil describes this genus in the following terms : — * 



" This little genus which Messrs. Eichwald and Pander have decided to separate from 

 the other Brachiopods, it appears to us deserves to be preserved. It is far removed from 

 Orlhis by the absence of an articulate hinge, by the nature of its test, and by the almost 

 equal valves, deprived of an area and of a triangular slit. It differs also from Crania, near 

 which Mr. Eichwald placed it, by the existence of a distinct hinge, also that it is without 

 teeth, by the regularity and equality of its A^alves, by their thin edges, and even by the 

 substance of the shell. "We observe as well as Mr. Pander the closest analogies between 

 those little shells and the Lingnlas, but we believe they ought not to be reunited, on 

 account of their transverse form, the width of their cardinal border and the canal with 

 which it is provided." '' 



[Beside Obolus Apollinis], " M. Eichwald has established three other species of Obolus, 



' " Palœoz. Fossils," vol. i, p. 21G, fig. iOl ; " Palseont. Eureka Dist.,'' p. 17, pi. i, figs. 1 a-b and d-f. 



' "List of the Fossil Faunas of Sweden," i, p. 7. 



^ ' Geol. Mag.,' vol. v, No 7, p. 313, pi. xvi, figs. 14-16. 



* ' Russia and the Ural Mts.,' Paris, 1845, vol. ii, p. 290. 



'" This objection does not applj' to the genus Lingrddla, to which these shells are much more closely allied than 

 they are to Lingula. The genus Lingulella was not separated from Lingula until 1861, fifteen years after these 

 remarks were written. 



