224 ROYAL SOCIETY OF CANADA 



large size show this variation of straightening out of the beak in early 

 growth and the full grown shells show high arched slopes on the surface 

 of the pedicle valve. 



17. Spirifer gaspensis, Billings. 



18. i^pirifer cumberlandiœ. Hall. 



19. Spirifera cydoptera, Billings not Hall {?^S. trihuUs, Hall). 

 There is in tliis lot a series of closely related forms which present 



the characters distributed by Hall under the names Spirifer submucro- 

 natus, Spirifer cumberlandiœ, Spirifer tribulis, and by Billings under 

 the names Spirifer gaspensis and Spirifer cydoptera, Hall, which upon 

 critical study I conclude represent the species cited above. 



17. Spirifer gaspensis, Billings, is represented by specimens of 

 both pedicle and bracliial valve, but no specimen shows the two valves 

 united. The brachial valves in size, plication and general form present 

 the typical characters figured by Billings. The species is said to have 

 12 to 18 undivided ribs each side the fold and sinus. Halls species, 

 Spirifer cumberlandiœ, is described as having 14 to 17 simple rounded 

 oosta?. Spirifer submucronatus is a smaller form and is described as 

 ha^dng 10-14 plications each side the fold and sinus. It is difficult to 

 name any characteristic by which these three shells may be sharply 

 distinguished. The exfoliated specimens of brachial valves from St. 

 Helen's bear greatest resemblance to Billings's species Spirifer gaspensis 

 under which they are here listed. 



18. Spirifer cumberlandiœ. Hall, 



Specimens showing the surface off pedicle valves well preserved 

 present the characters given by Hall to his species Spirifer cumberlandiœ 

 when of corresponding size, and a small specimen well represents 

 Spirifer submucronatus, Hall. Upon comparison I find the smaller 

 specimens present the same characters which distinguish the correspond- 

 ing part of the large specimen, for which reason I list both as one 

 species, under the name Spirifer cumberlandiœ. Still other specimens 

 of pedicle valves in which the shell is removed in breaking the rock, 

 exposing the interior of the pedicle valve, show the prominent tongue 

 like extension representing the rostral cavit}^, at the bottom of which is 

 trace of the muscular impressioins, as seen in both Sp. gaspensis and S. 

 cumberlandiœ, and still more prominently in Sp. murchisoni. These 

 pedicle valves I conclude belong to the same species afe do the brachial 

 valves here identified with Sp. gaspensis. They differ from Billings's 

 figure of the latter species by having the shell above the hinge and out- 

 side the teeth plates thickened to a greater degree, and in this particular 

 agree better with Hall's figure of Sp. cumberlandiœ (93 of Plate 96), 



