il6 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 64 



An attempt will be made during the field season of 1914 to dis- 

 cover the mode of growth and the extent of this species. It is 

 unusually interesting owing to its resernblance to the deposit made 

 by the Blue-green Alg?e in the fresh-water lakes of New York, 

 Michigan, and elsewhere. 



Formation and locality. — Algonkian : (400c) Beltian series: New- 

 land limestone : 8 miles ( 12.8 km.) west of White Sulphur Springs at 

 forks of Birch Creek, Meagher County, Montana ( M. Collen, 1906.) 



GALLATINIA, new genus 



As there is but one species of the genus known the generic and 

 specific description is united for the present in the description of 

 the species. 



Genotype. — Gallatiiiia perfcsa, new species. 



Stratigraphic range. — As far as known it is limited to a few layers 

 of limestone in the central portion of the Algonkian section of the 

 Gallatin Valley. 



Geographic distribution. — North side of Gallatin and East Galla- 

 tin Rivers, between Gallatin Station and Dry Creek, Gallatin County, 

 Montana. 



GALLATINIA PERTEXA, new species 

 Plate 23. figs. I, 2 



External form discoid, circular, flattened. In a specimen 21 cm. 

 in diameter there is an outer border about 3 cm. in width and 4 cm. 

 in depth that extends from the base to the upper surface of the 

 specimen. This outer ring is united to the center by seven ray-like 

 arms arranged in a more or less irregular manner. The outer border 

 ring is formed of fine, irregular lamellae that slope inward more or 

 less from the base to the upper surface. The radiating arms are 

 formed of a series of A'-shaped lamellae that extend down into the 

 mass of the specimen a distance equal to about their w'idth at their 

 upper surface. The border ring and arms are connected by a mass 

 of vesicular lamellae that fill the interior of the specimen. At the 

 upper surface between the radiating arms the vesicular lamellae 

 form more or less concentric lines about the center. 



The photographs of the specimen show the details of structure 

 fairly well. 



The specimen is formed of a siliceous, bufif-weathering material 

 with a filling in all interspaces of dark, bluish-gray limestone that 

 is readily removed in solution by weak hydrochloric acid. 



