COASTS VISITED BY THE AKCTIC EXPEDITION". 631 



marked variety than usual, nevertheless it can be no other than 

 the above species. Like P. mesolobus this shell is found over the 

 northern hemisphere, both in Europe and America, as far north as 

 land is known. Collected by Capt. Feilden at Feilden Isthmus, 

 lat. 82° 43'. 



Productus costatus, Sow. 



Productus costatus, Sow. Min. Con. vol. vi. p. 115, t. 560 ; De 

 Verneuil, Russia and the Ural Mountains, vol. ii. t. 15. f. 13; Dav. 

 Monogr. Carb. Brach., Pal. Soc. p. 152, t. 32. f. 2-9. 



This is the most abundant and at the same time most variable 

 species in the collection of the Carboniferous Brachiopoda, no less 

 than fourteen specimens occurring from the beds at Feilden Isthmus. 

 De Verneuil has noticed this species from many places in Russia ; it 

 also occurs at Vise, in Belgium. It is abundant in the Scotch and 

 Irish Carboniferous Limestones. Settle, Richmond, and places in 

 Northumberland also yield this species. Doubtless it must be very 

 abundant in the limestones of Feilden Isthmus ; it is the commonest 

 form in the collection. In North America it is widely distributed 

 through the limestones of Kansas, Missouri, Iowa, Illinois, and 

 Indiana, also in Nova Scotia. We should therefore expect to find 

 it extending northwards, in the original great spread of the Carbo- 

 niferous series towards the Pole. With P. Cora, P. Flemingii, 

 P. punctatus, and P. semireticulatus it has the widest range of any 

 species on the American continent, and is associated with the last 

 two at Feilden Isthmus. 



Log. Feilden Isthmus, lat. 82° 43'. 



Productus Weyprechti ?, Toula. 



Productus Weyprechti?, Toula, Sitzungsberichte der kais. Akad. 

 der Wissenschaften in Wien, p. 138, 1. 1. f. 4. 



The determination of this shell has given me much trouble. I can 

 refer it to no other than the above species of Toula's. Much as it 

 resembles some forms of P. costatus, it is not, however, that species, 

 the sulcus in the ventral valve being deeper and wider in proportion, 

 and extending along the central portion of the valve in nearly uni- 

 form width and depth. It may readily be taken for Productus 

 horridus, from the Permian series ; but the greater depth and square- 

 ness of the ventral valve, also the pronounced sulcus and apparent 

 greater solidity of the shell, remove it from that species. When, 

 however, we know the extreme variations these shells (especially 

 P. horridus) undergo, and only three imperfect specimens are in the 

 collection, it is not an easy matter to determine their specific identity. 

 I refer them, however, to one or other of the above species, P. Wey- 

 prechti or P. horridus. Toula's specimens came from Spitzbergen, 

 and were collected during the Austrian expedition to the Polar 

 regions. 



Log. Cape Joseph Henry, lat. 82° 50'. 



