1855.] ISBISTER — NORTH AMERICA, ETC. 519 



however, before a complete and connected view of the geological 

 structure of this portion of the American Continent can be obtained. 



Fossils of the Carboniferous Formation. — The limestones of this 

 formation, which have been traced at several points along the coast 

 (see Map, PI. XIV.), are most extensively developed in the N.E. ex- 

 tremity of the Continent, where they occupy the greater part of the 

 coast-line from the north side of Kotzebue Sound to within a few 

 miles of Point Barrow, and form the chief constituent of the lofty 

 and conspicuous headlands of Cape Thompson, Cape Lisburn, and 

 Cape Sabine. Near the last-named cape a vein of excellent coal is 

 exposed, which burns with a good heat and a bright flame. The 

 limestone is, according to Dr. Buckland, scarcely distinguishable from 

 the Mountain Limestone of Derbyshire. Some specimens brought 

 to England by Captain Beechey were found to contain Lithostrotion 

 basaltiforme {Cyathophyllum basaltiforme, Phil. G. Y.), Flustra^ 

 Froductus Martini, Dentalinm, several varieties of Terebratula, and 

 a great abundance of Encrinital fragments, with the detritus of which 

 the rock was in many places almost entirely made up. To these 

 Dr. Grewingk adds, from the collections of Russian explorers, Cya- 

 thophyllum Jlexuosum, Goldf., TurbinoUa mitrata. His., Cyatho- 

 phyllum dianthum, Goldf., and Sarcinula, together with some Spiri- 

 feri, Orthidce, and Terebratidce. 



Remains of Coniferous plants, belonging to the genera Abies and 

 Taxodium, and of some Ferns, among which is Neuropteris acutifoliay 

 have been discovered among the islands along the S. coast of Aliaska. 



A specimen of Catenipora escharoides, found in a rolled fragment 

 on the island of Sitka, would appear to indicate the existence of Si- 

 lurian deposits in the neighbourhood ; but no organic remains from 

 rocks of this formation in situ have hitherto been discovered. 



Jurassic Fossils. — Four fossils found in Katmai Bay, on the 

 south coast of the promontory of Ahaska, have been referred by Dr. 

 Grewingk, on the authority of M. Wosnessensky, OUrator of the Zoo- 

 logical Museum of the Academy of Sciences of St. Petersburgh, to the 

 Jurassic formation. They include a new species of Ammonite, A. 

 Wosnessenskii, Ammonites biplexl. Sow., and fragments of Belem- 

 nites paxillosus and Unio liassinus. Myen (Nov. Act. Phys. torn. 

 xvii. pi. 47. figs. 1 & 2) figures an Ammojiites biplex from some Ju- 

 rassic deposits at the foot of the volcano of Maipu, in the Andes, S. 

 of Valparaiso, which cannot be distinguished from the specimen from 

 Aliaska. It may be doubted, however, whether upon such scanty 

 evidence the existence of deposits of Jurassic age in these high lati- 

 tudes can be considered as estabhshed ; no other indication of the 

 existence of this formation having been hitherto discovered in any 

 part of North iVmerica north of the United States. 



Tertiary Fossils. — Traces of the Tertiary formation have been dis- 

 covered at various points between Oregon and Aliaska, but not be- 

 yond. This striking and well-marked division of the coast may, 



