THE FAUNA OF TIIK ST. JOHN GROUP. 3 S 



The hinge area and Ibraminal grove of Lingnlella are well displayed in the ventral 

 valve of this species. 



Another, radially ribbed species oî Lingulella (?) occurs in the fine shale of Div. ^..d; 

 bvit the material is too imperfect for description. 



LINNARSSONIA, Walcott. 



Mr. C. D. Walcott proposes this as a new genus to include Obolella transversa (Hartt), of 

 the St. John group, and 0. sagiUaJis (Salter), of the Welsh Cambrian. The St. John species, 

 of which there are two, differ from the types of Obolella in the form of the muscular scars 

 and in the substance of the shell, which is more or less phosphatic or horny. On account 

 of the differences in the muscular impressions, etc., Mr. Walcott separates those shells 

 under the above name. (See American Journal of Science, III, Vol. XXIX. No. 1*70, p. 115). 



LiNNAESSONiA TRANSVERSA, Hartt, sp. (Plate Y. Figs. 11, llrt, b, c, d, and e) 



Obolella transversa, Hartt. Acad. GeoL, 2ud Ed., p. 644. U._S. Geol. Surv., Bull. 10, PI. 

 I. Figs. 5 and oa. 



This is one of the earliest species of the St. John group, since it is found as low down 

 as the first layers of the group b in Div. 1. It ranges upward through b, c, and d. 

 as far as the latter member has been explored. It has a thicker shell than the other 

 smaller brachiopods associated with it, and is therefore less distorted than the other small 

 species. The examples which exhibit most clearly the generic character of this species 

 are found in the dark shales of l.d. From these it may be seen that, in the form of the 

 median furrows of the dorsal valve, it is quite distinct from L. sagiltalis (Salter). There 

 are differences of proportion in the internal characters of the ventral valves of the two 

 species. This may be seen by reference to Mr. Walcott's Note, establishing the genus 

 Limiarssonia [Am. Jour. ScL, Feb., 1885.) The affinities of this genus to Acrotreta, especially 

 to the forms in the Paradoxides beds, are apparent. 



LiNNARSSONiA MISERA, Billings, sp. (?) (Plate V. Figs. 12, 12a, b, c, d and e.) 



Obolella {?) misera, Billings. Palœozoic Fossils, Yol. II. Part I. p. 69. 



The fine shales of Div. l.d contain numerous examples of a little shell which appears 

 to be identical with this species. It occurs in the same measures as L. transversa. The 

 writer gives the following characters to distinguish the two species : — 



In L. misera the valves are flatter and the hinge line longer. The shell substance is 

 • thinner, and often does not exhibit so decidedly the black colour which marks the thicker 

 vah'es of L. transversa. 



The dorsal valve is somewhat lower at the umbo than the corresponding valve of 

 that shell, and the internal median ridge is narrower, sharper, and less conspicuous ; it 

 extends across the umbonal hollow as a thin thread-like line ; the muscular scars are 

 smaller and closer to the umbo. 



The ventral valve has a small hinge area, and a more faintly marked apical pit than 



