June 1, 18S3.] 



SCIENCE. 



477 



ending at the apex of the modiohis. A larger 

 spiVaZcawaZ traverses' it just behind and along 

 the course of the spiral lamina, for the accom- 

 modation of the spiral ganglion. Numerous 

 fine canals, communicating with the minute fo- 

 ramina of the spiral tract, likewise traverse the 

 modiolus, for the transmission of the filaments 

 of the cochlear nerve. The canals iu their 

 advance are successively reflected to open into 

 the spiral canal of the modiolus. 



The spiral lamina is composed of two delicate 

 compact laj'ers, with an intervening delicate 

 spongy laj'er, which is traversed with numerous 

 fine radiating and anastomosing canals. These 

 communicate with the spiral canal of the modi- 

 olus, and terminate in minute apertures at the 

 free edge of the spiral lamina. 

 . The tj'mpanic passage of the cochlea is di- 

 rected from the round window downwai'd, for- 

 ward, and inward. It is crossed below, just 

 in advance of the window, by a little crest,' 

 to the inside of which is the aperture of the 

 fine venous canal communicating with the pj'r- 

 amidal pit of the jugular foramen. The ves- 

 tibular passage communicates with the vestibule 

 internally to and above the tympanic passage, 

 and below the position of the oval window. 



The round window looks outwardl}' from the 

 tj-mpanic passage into the arched recess at the 

 back of the promontory'. It is beneath and a 

 little external to the position of the oval window, 

 from which it is separated b}' a vaulted arch 

 formed b}' the upper part of the laromoutoiy. 

 It is irregularlj' circular or somewhat oval, and 

 about a third less in size than the oval window. 



GLACIAL DEPOSITS OF THE BOW AND 

 BELLY RIVER COUNTRY. 



During the progress of the geological exami- 

 nation of the Bow and Belly River country, 

 which lies for the most part in the drainage- 

 area of the South Saskatchewan, north of the 

 49th parallel, and immediately- east of the base 

 of the Rock}' Mountains, several points of con- 

 siderable interest and importance in the his- 

 tory of the glacial period have been observed. 

 These observations, though made in the summer 

 of 1881, have not yet been published ; and, as 

 it is hoped that the work of the coming season 

 maj' add largely to our knowledge of this and 

 neighboring districts, a detailed report is like- 

 ly to be still further deferred. A brief general 

 notice may in the mean time be of interest to 

 the readers of Science. 



A s^'stematic account of the ' surface geolo- 

 gy ' of this and other districts iu the ■\'icinitj' 



1 Crista semilunaris. 



of the 49th parallel was first given by the 

 writer in 1875.^ Observations were, however, 

 at that time, necessarily' confined more or less 

 closely to the neighborhood of the 49th paral- 

 lel. The late examination of the Bow and 

 Bellj' country has been much more complete, 

 embracing an area of about 20,000 square 

 miles. The surface of this region declines, but 

 not uniformly, from a height exceeding 4,000 

 feet along the base of the mountains to about 

 2,500 feet in its eastern and north-eastern parts. 

 With the exception of a strip of country which 

 may be designated as the foot-hills of the 

 Rocky Mountains, the whole of this tract is 

 covered more or less deeply with material which 

 may be generallj' referred to as ' drift.' Over 

 considerable areas this covering is from 100 to 

 200 feet in thickness ; but in other places it is 

 comparatively scanty, particularlj' on some of 

 the more elevated plateaus of cretaceous and 

 Laramie rocks. During later tertiary time the 

 country has evidently been subjected to very 

 extensive denudation ; and its surface must 

 have been much more diversified at the onset of 

 the glacial period than it is at present. The 

 drift deposits have evidently filled pre-existing 

 hollows and low tracts ; and the general effect 

 has been a filling-up of its irregularities, and the 

 l^roduction of wide areas of almost level prairie 

 countiy. In cutting out their beds anew in the 

 modern period, the rivers have in some places 

 exposed fine sections of the cretaceous and 

 Laramie rocks, while in others the base of the 

 drift deposits has not been reached. 



Resting immediatelj' on the surface of the 

 cretaceous and Laramie rocks in a number of 

 localities on the Bow, Belly, Old Man, and other 

 rivers, is a deposit of well-rolled pebbles or 

 shingle, consisting, for the most part, of hard 

 quartzites, and derived entirely' from the pale- 

 ozoic rocks of the Rocky Mountains. These 

 pebbles are seldom more than a few inches in 

 diameter, and often verj' uniform in size. The 

 deposit has been observed to extend to a dis- 

 tance of over a hundred miles from the base of 

 the mountains. Whether it has been carried 

 from the mountains entirely b^' the action of 

 rapid streams of pregiacial times, or has been 

 distributed in some more extended body of 

 water, I am as j'ct unprepared to decide ; but 

 the fact that it occurs at very different eleva- 

 tions above the present water-level in neighbor- 

 ing sections on the same river, would appear 

 to point to the latter conclusion. No marks 

 of ice-action have been found on the stones of 

 this deposit, which at one place on the Belly 



' Quart, journ. ijeol. sec, Nov., 1S75. Geology and resources 

 of thii 49th parallel. 



