400 



THE AMERICAN NATURALIST 



[Vol. XLI 



A Preliminary Note on the Variation of Scutellation in the Garter 

 Snakes.— Three years ago the writer began an investigation into the 

 relationships of the different races of garter snakes (Thannophis) in 

 an attempt to determine the laws involved in the differentiation of 

 the genus. The results of this work are being included in a mono- 

 graph of the genus, but as it will be several months before this work 

 can be completed it has been thought best to publish a brief outline 

 of some of the conclusions. 



In the progress of this investigation it was seen very early that before 

 a serious attempt could be made to determine the affinities of the 

 different races, the significance of the variations in scale arrangement 

 or scutellation must be determined. This was attempted with the 

 following results: 



(1) The number of dorsal scale rows on an individual snake 

 decreases posteriorly by the elimination of certain rows, and 

 the series eliminated are always the same for snakes with the 

 same number of rows, as for example T. sirtalis and T. saurita. 



(2) The rows dropped posteriorly in individual snakes are those 

 which have entirely disappeared in races with a fewer number 

 of scale rows. 



(3) The reduction in the number of dorsal scale rows is generally 

 accompanied by a reduction in the number of labial, ventral, 

 and subcaudal scales (gastrosteges and urosteges). 



(4) There is considerable evidence that the reduction in scutella- 

 tion is directly or indirectly associated with a diminution in size. 



The general reduction in scutellation described above is exhibited 

 by each of the several (natural ?) groups into which the genus can be 

 di\ided. These groups all occur together only in northern Mexico, 

 which may be considered the center of origin for the genus. The 

 races that occur in this region all exhibit the maximum scutellation 

 for their respective groups, the dwarfing in size and scutellation 

 taking place at points away from the center of origin. The dis- 

 covery of these methods of variation in the different series of scales 

 has been an indispensable aid in determining the affinities of the dif- 



A Simple Method for removing the Gelatinous Coats of Eggs.— 



of amphibian eggs tlie writer liir iij)i>ii a -iinph' jind ra{)id method of 

 freeing them from their irclannous eiiv( l()iH>. While, because of its 



