220 Penfield and Sperry — Composition of Howlite. 



antiquity and distinctness from the alluvium proper.* Now 

 the New Madrid specimen appears to have come from the Port 

 Hudson beds ; and the Fort Gibson Specimen was obtained 

 from a puzzling superficial deposit found in Missouri, southern 

 Kansas, Indian Territory, Eastern Texas, and Arkansas, which 

 is conspicuous along the water- ways but attenuates and fre- 

 quently disappears over the higher lands, and which seems to 

 be a slack-water deposit laid down in the waterways of the 

 region during the Fort Hudson submergence. The paleontolo- 

 gic correlation is therefore perfectly consonant with the physi- 

 cal, and the two lines of evidence are cumulative. The evi- 

 dence of the fossils is of exceptional value, too, when, like 

 Ovibos and Rang if er, they represent an arctic fauna ; for not 

 only are vertebrates the most sensitive time indicators, by 

 reason of the evanescence of types, as shown by Marsh, but 

 when the remains of arctic animals are found in temperate lati- 

 tudes it is manifest that they indicate only a temporary incur- 

 sion of the fauna, and therefore represent but a small portion 

 of the period covered by the phylogeny of the species. 



Art. XXVI. — On the Chemical Composition of Howlite, with a 

 note on the Oooch method for the determination of boracic acid / 

 by S. L. Penfield and E. S. Sperry. 



This interesting mineral was first identified as a new species 

 by Prof. Henry How,f of Windsor, Nova Scotia, who named 

 it silicoborocalcite, assigning to it the composition 2CaO . SiO,+ 

 2(Ca0 2 . B0 3 . HO) + B0 3 . 3HO, written in the old system and 

 in the form suggested by Prof. How. He described it as 

 occurring in dense, chalk-like nodules in the gypsum beds at 

 Brookfield, near Windsor, N. S. In later papers^ he mentions 

 its occurring in four distinct localities near Windsor, the 

 nodules being sometimes as large as a man's head and com- 

 posed of minute scaly and silky crystals. The name howlite 

 was substituted for silicoborocalcite by Prof. J. D. Dana and 

 used by him in the fifth edition of his System of Mineralogy. 



The specimen which we have examined was collected in the 

 gypsum quarries at Windsor, N. S., by Mr. Charles G. Rupert, 

 of Minneapolis, Minn., who generously presented it to the miner - 

 alogical department for investigation. It consisted of an egg- 

 shaped nodule about one and one-half inches in its greatest 

 diameter, embedded in massive gypsum. The nodule was 

 composed of intergrown microscopic needles which under the 



* This Journal, III, vol. ii, 1871, 402. 



f Phil. Mag., IV, xxxv, p. 32. 



\ Phil. Mag., IY, xxxvii, 270 and xxxix, 278. 



