187 



Sculpture. The surface is marked by minute concentric beaded lidges, 

 visible only with a strong lens ; there are stronger growth lines at 

 intervals. 



Size. Length, 3 mm. Width 3 mm. Height of the ventral valve, 

 one-fifth to one-quarter less. 



Horizon and locality. The fine dark gray shales of the Dictyonema 

 beds (C. 3c.) at McLeod brook, Cape Breton. 



On re-examining the specimens from this horizon at Navy island, St. Compared 

 John, KB., which I had compared with A. Baileyi, of the Paradoxides with . other 

 beds, I find they are of a species identical with that from McLeod brook. 

 It is distinguished from A. Baileyi by the long, sharp median ridge of the . 

 interior of the dorsal valve ; the convex summit of the mould of the ven- 

 tral valve also distinguishes it from that species, in which the summit 

 is concave, and porportionately smaller. 



From A. socialis, Von Seebach,* this species is distinguished by its 

 somewhat larger size, and by the absence of the sharp wedge-shaped 

 furrow in the top of the mould of the ventral valve ; by the absence of 

 the strong lateral furrows in the mould of the dorsal valve of that 

 species ; also by the deeper and longer mesian furrow of the dorsal valve 

 of the McLeod brook species. 



From A. gemma, Walcott,f this species is distinct by the convex top of 

 the mould of the ventral valve, by the absence of an area to the dorsal 

 valve, and the enlarged posterior end of the median ridge in this valve. 



From A. gemmula\ this species is distinct by the larger size, convex 

 summit of the ventral mould ; and by the smaller scars of the 'posterior 

 adductots and sharper and longer median ridge of the dorsal valve. 



SCHIZAMBON PRISCUS, Plate xi., figs. 6a-e?. 



Bull. Nat. Hist. Soc. of N. B., vol. iv, p. 277, pi. v., figs. 4 a to d. 

 Shell substance firm, corneous (or calcareo-corneous 1 ). Outline orbi- 

 cular, and valves lenticular and of moderate depth. Schizambon 



priscus 

 Ventral valve with a rounded umbo, the greatest depth in front of the described. 



umbo, about two-thirds from the front. About one sixth or one eighth 

 from the posterial margin, the valve is perforated by an oval foramen, in 



*Brachiopoda of the Paradoxides beds of Sweden. G. Linnarsson, Stockholm, 

 1876, p. 16, pi. iii, figs. 32-35. 



tU. S. Geol. Surv. Bull. No. 30, p. 98, pi. viii, figs. la-6. 

 +Roy. Soc. Can. Trans., vol. xi, sec. iv, p. 87, pi. xvi, fig, 2a-d. 



