Febrtjaby 14, 1908] 



SCIENCE 



273 



cited here. Of the 100 persons to whom the 

 right disc appeared larger, 76 were right- 

 handed, 8 ambidextrous, 16 left-handed. Of 

 the 45 persons to whom the left disc appeared 

 larger, 15 were right-handed, 3 ambidextrous, 

 27 left-handed. These results can not be con- 

 sidered final; but, they do seem to indicate a 

 tendency to a relationship between the periph- 

 eral perception of size and right- and left- 

 handedness. 



Granted that such a difference in the per- 

 ception of size does certainly exist between 

 the central and peripheral parts of the retina, 

 the sensory motive, so to call it, which in the 

 discussion of the part played by the left hemi- 

 sphere, seemed necessary to initiate right- 

 handed movements, would be furnished. Ob- 

 jects situated in the right half of the field of 

 vision of a left-hemisphered infant would, by 

 appearing larger, attract its attention. The 

 eyeballs would then turn, reflexly, to receive 

 the attractive object on the fovea. Eye move- 

 ments would, probably, lead to head move- 

 ments, and head movements to arm move- 

 ments. Just the reverse of this would happen 

 with a right-hemisphered infant. The fact 

 that the predominant use of the right hand 

 is developed by trial and error, is against the 

 assumption that there is a " natural prepotency 

 in the paths to discharge into the right arm." 

 If it were merely reflex, there would be no 

 period of uncertainty in which both arms are 

 used. A fact which supports the view sug- 

 gested here is that the time (seven months) at 

 which a pronounced right-handedness de- 

 veloped in Baldwin's' child was but little later 

 than the time (five months) at which Eaehl- 

 mann° found that an object was recognized 

 when its image fell on the periphery of the 

 retina. H. C. Stevens 



Seattle, Washington 



tertiary deposits op northeastern mexico 

 The work done in the Tertiary deposits 

 ' " Mental Development, Methods and Processes," 



p. 64. 



^ Cited, without reference to the original, by 



Schaefer, " Text-book of Physiology," Vol. II., 



p. 75». 



along the Eio Grande border of Texas by Dr. 

 E. A. F. Penrose, Jr., and myself, and de- 

 scribed in the First Annual Eeport of the 

 Geological Survey of Texas and in a later 

 paper entitled " Geology of Southwestern 

 Texas," has been extended southward during 

 the past year by Professor W. F. Cummins 

 as far as the Conchas Eiver. 



He finds that the same general divisions 

 which we have described in Texas are easily 

 recognizable for this entire distance of more 

 than one hundred miles, but also finds that, 

 while a large number of the familiar forms 

 of the Texas fossils are found in the various 

 divisions, there are others which were not 

 recognized there. Among these is the occur- 

 rence of a Venericardia, which Dr. Dall states 

 is allied to poiapacaensis of the Maryland 

 Eocene, in beds that are stratigraphically the 

 continuation of the Marine stage of the Texas 

 section. A number of other new forms were 

 also found, which have not as yet been studied. 



The beds of the Fayette stage which are 

 exposed on the Eio Grande between Carrizo 

 and Eoma extend southward to Mendez on the 

 Conchas and are characterized by the large 

 Ostrea alabamiensis var. contracta Conrad 

 and other forms. 



The beds of the Frio stage which overlie the 

 Fayette here, as farther north, are better ex- 

 posed in this region than in Texas and carry 

 a very distinctive fauna. Some of the forms 

 collected at San Fernando on the Conchas 

 Eiver were examined by Dr. Dall, who writes 

 that they comprise Pecten, Area, dementia, 

 etc., and are with little doubt Oligocene. This 

 series of beds, which Professor Cummins calls 

 the San Fernando, was traced by him to the 

 extreme southern limit of the Tertiary, some 

 forty miles south of the mouth of the Soto 

 Marina Eiver. 



Very few fossils were found in the Frio 

 deposits in Texas and such as were determin- 

 able seemed to warrant its reference to the 

 Eocene, but Professor Cummins's later dis- 

 coveries show this to be incorrect and in place 

 of being of Lower Claiborne age, it should be 

 placed with the Oligocene. 



E. T. DUMBLE 



