BRACHIOPODA. 115 



We have before us an excellent series of specimens representing a species 

 which has l)oen described as Siphonotreta, from dark limestones intercalated 

 between shales at Gloucester, Ontario ; beds referred to the age of the 

 Utica slate of New York. The first mention of these fossils was by Mr. J. F. 

 Whiteaves, in a paper read before the Montreal meeting of the American 

 Association for the Advancement of Science, in 1H83; subsequently a more 

 detailed account of their occurrence and association was given by Mr. H. M Ami, 

 in the Ottawa Naturalist for December, 1887. To these gentlemen we are 

 indebted for the opportunity of stud\-ing the fossils. Mr. D.avidson, who ex- 

 arained the Canadian specimens sent him by Mr. Whiteaves, identified 

 them with his species Siphonotreta Scotica* but certain differences indicated by 

 Mr. Ami induced the latter to propose therefor the varietal term Canadensis. 



The general features of these specimens and the numerous fine, smooth 

 spines, indicate a close similarity to Davidson's species ; but in the material 

 received from Mr. Ami are two pedicle-valves, one of which, shows the ex- 

 terior character of the pedicle-passage, and the other somewhat of its internal 

 extension. The former shows this passage to be of precisely the character of 

 that seen in Kutorga's S. fissa (see Plate IV, figs. 31, ;^3), and the latter (idem, 

 fig. o4) demonstrates that the interior extension of the sipho was carried as 

 far forward as the center of the shell.f 



Upon comparison of these specimens with Kutorga's description of S. fissa, 

 we find an agreement in almost every particular ; the .shell has the " depressed 

 Terebratula-like form" in distinction from other species of the genus; the 

 striae of growth, fine and sharp about the apex, become broad and thick toward 

 the margins ; the spaces between the rows of spines are smooth or crossed by 

 extremely faint radiating lines ; added to this is the character of the pedicle- 

 groove, its floor being crossed by fine, successive growth-lines. Oidy in the 

 relative number of the surface spines does there appear any difference. 

 In the Rus.sian species these are described as a mass of smooth, hair-like 



* Silurian Supplement, p. 218. 1883. 



f Mr. Davidson described his Scottish species .IS having :iu '-acuminated beak, perforated at its ex- 

 tremity by a small circular foi-aminal aperture " (Geol. Ma^., 1S77. p. 13). It is therefoi-e evident that the 

 Canadian species is widely different from S. Scotica. 



