42 



JOHAN KIjER. 



[sec. ARCT. EXP. FfiAM 



In the case of B. canadensis the measurements are partly detei'- 

 mined from examples from Scaumenac Bay, partly from Traquair's 

 reconstruction, and in the case of B. hydrophila from Traquair's ^ 

 excellent illustrations and reconstruction. 



Length of unt. 

 Length of , ventr. later, 

 proximal part ^ i^late from post, 

 of arm. | niarg. to inner 



cross rib. 



Proportion 

 Figure. 



1. Form from Galgeodden, EUes- 

 niere Land . . 



2. B. canadensis Whit. Specimen 

 from Scaumenac Bay . . 



3. B. canadensis Whit. Traquair's 

 reconstruction . . . 



4. B. hydrophila Ag. Traquair's 

 reconstruction 



19 mm. 33 mm. 



42 



25 



58 



31 



17- IS 



31-32 



1 : 1.74 



1 : 1.38 



1 : 1.24 



1:1.8 

 1 : 1.77 



As will be seen, the form described differs very considerably from 

 B. canadensis Whit, but agrees almost entirely with B. hydrophila Ac. 

 which is known in excellent specimens from Dura Den in Fifeshire, 

 Scotland in the Upper Old Red Sandstone. 



Since also according to Traijuair's description the sculpture, the 

 short and broad form of the anterior body plates, and the size on the 

 whole agree in the two forms, J may presume that tlie remains from 

 Ellesmere Land are either identical or nearly related to B. hydrophila 

 Ag. I have not been able to discover any American form showing closer 

 agreement. The most nearly related appears to be B. canadensis Whit 

 which, however, has considerably shorter arms. 



It is difficult to determine exactly whether the fragments with coarser 

 sculpture also belong to B. hydrophila. Ag. The variations of sculpture 

 and dimensions in the case of B. canadensis Whit, show that these 

 fragments may possibly belong to the same form as the others. One 

 fragment, however, shows so coarse and so markedly nodose ribs, that 

 it can scarcely belong to the same species. 



Horizon. From the dark schists of Galgeodden, with remains of 

 plants, — and fi'om the fish horizon of Skrap Valley. 



1 R. H. Traquair. The Asterolepidee, Monogr. Pal. Soc. 1894 and 1904. 



