Port Clarence Limestone, Alaska. 345 



Mhynchonella ? n. sp. 

 Triplesia extans Hall. 



Pelecypoda : 



Modiolopsis cf. faba Hall. 

 " sp. undet. 



Gastropoda : 



Patelloid shell suggesting Stenotheea unguiformis Ulrich. 

 Maclurea bigsbyi Hall. 

 Lophospira sp. undet. 

 Hormotoma cf. gracilis Hall. 



" cf. bellicincta Hall. 



Eotomaria ? sp. undet. 

 Trochonema sp. undet. 



Tkilobita : 



JBumastus sp. undesc. (near one in beds of lower Mohawkian 

 age in Minnesota). 



Judging from the general aspect of this fauna of 26 species, it 

 seems unquestionably Ordovician in age. The forms of Halysites 

 also are of the type found in the lower part of rocks of Trenton 

 and Black River age in Minnesota and Wisconsin, and later of 

 the Mississippi Valley and elsewhere." 



Station 13b includes about 100 feet of limestones imme- 

 diately north of the mouth of the ravine mentioned above, and 

 lying stratigraphically probably 200 feet higher. This lime- 

 stone is exposed in the low bench just south of a small draw 

 and contains a great profusion of corals in which Halysites is 

 conspicuous. Brachiopods are not uncommon, but less abun- 

 dant. The following is a list of the fauna found there as 

 determined by Mr. Ulrich : 



" Corals : 



Columnaria alveolata Goldfuss. 



" ? cf. goldfussi Billings. (Can not be distin- 



guished from basal Trenton form except by closer 

 arrangement of its tabulae.) 

 Calopoecia canadensis Billings. 

 Halysites gracilis Hall. 



" " var. with small corallites and very small 



meshes. (Very much like a form in the Silurian at Wisby 

 Gotland, received from Lindstrom.) 

 Stromatocerium ? sp. undet. 



Brtozoa : 



Nicholsonella ? sp. undet. 



Brachiopoda : 



Leptazna tenuistriata Hall. 

 Hebertella ? sp. undet. 

 JRhynchotrema capax ? Conrad. 



Am. Jour. Sci. — Fourth Series, Vol. XXXII, No. 191.— November, 1911. 

 26 



