COASTS VISITED BY THE ARCTIC EXPEDITION. 635 



being exposed ; in other words, we have only a single valve (dorsal), 

 and this partly imbedded in the matrix. It is as variable a shell 

 as Sp. disjuncta, Sow., which has received about twenty different 

 names. Hall describes the shell as having a ventricose dorsal valve 

 and prominent rounded mesial fold, rather prominent beak, and area 

 somewhat large, about twenty simple plications on either side of the 

 sinus (our specimen has not so many, twelve to fourteen). Wo shell 

 being left, we have no means of knowing whether granulose longi- 

 tudinal striae existed (as in Hall's shells) or not, these being seen 

 only on well-preserved specimens. The five varieties named by Hall 

 and his descriptions tend to show the variability of these Spiriferidae. 

 The Hamilton group in Maryland, Virginia, Pennsylvania, New- 

 York State, Erie and Genesee county yield this shell. Our speci- 

 mens come from Ravine, Dana Bay, lat. 82° 42', from beneath the 

 Carboniferous series of Feilden Isthmus. 



Oethis?, Chonetes or Steeptoehtnchtis. (PI. XXIX. fig. 4.) 



This one specimen may be either a Chonetes or Streptorhynchus ; 

 the hinge-line being hidden, we have no good characters to aid us 

 in determination. 



hoc. Feilden Isthmus, lat. 82° 43'. 



Productus, sp., allied to P. costattjs or P. mesolobus. 



This single specimen is evidently of the same species as those I have 

 referred to as Productus costatus from the Carboniferous Limestone 

 of Feilden Isthmus ; it is, however, associated with those coarsely 

 costated and broadly winged Spiriferce which characterize the De- 

 vonian rocks. From Captain Feilden's notes the beds containing 

 these shells must underlie the Carboniferous series, or be at their 

 very base ; and this adds strength to the grouping adopted for their 

 reception between the Upper Silurian and Carboniferous series. No 

 Productus appears to be known in the Devonian rocks of Canada, 

 and there are only three or four from the Devonian of North 

 America. Strophalosia is its representative genus in the British 

 Devonian rocks of North Devon, &c. The genus Productus is essen- 

 tially Carboniferous in specific value ; its association with Spirifera 

 pennata, Sp. AldricM, and Sp. granulifera is confirmatory of its 

 stratigraphical position. 



Loc. South of Feilden Isthmus, lat. 82° 43'. 



EXPLANATION OF PLATES XXV.-XXIX. 

 Plate XXV. 



Fig. 1. Monograptus ccnvolutus, His., var. Coppingeri, Eth., p. 577 



Figs. 2, 3. Pentamerns Copping eri, Eth., p. 594. 



Fig. 4. Strophodonta Feildeni, Eth., p. 598. 



Fig. 5. Spirifera, sp., allied to S. Grimed, Hall, p. 628. 



