180 SHIMER AND GRABAU — HAMILTON GROUP OF THEDFORD 



listed by Whiteaves, but not contained in our collections. For purposes 

 of comparison, we have also recorded the distribution of these species at 

 Eighteen-mile creek and vicinity. 



The following notation has been used : 



c = common. 



C = very common. 



r = rare. 



R — very rare. 



re = fairly common. 



cf= identification only open to question. 



? = horizon only open to question. 



Cn = recorded by Calvin. 



S = recorded by Schuchert (Whiteaves' 



list). 

 W = recorded by Whiteaves. 



It will be found useful to bear in mind the following notes when con- 

 sulting the table : 



a. Orthoceras exile is found only in the Strophalosia bed at the base of the Ham- 

 ilton, in the Eighteen-mile Creek region (Grabau 1). 



b. Phanerotinus laxus. This is characteristic of the shales below the Stropha- 

 losia bed or basal Hamilton at Eighteen-mile creek (Grabau 1). 



c. Loxonema sp. Two species are abundant in the Strophalosia bed at Eighteen- 

 mile creek ; another occurs in the Encrinal limestone, and still another in the 

 lower shales (see Grabau 3, 1899). 



d. Nuculites triqueter. This occurs only in the Upper Marcellus and Transition 

 shales of the Eighteen-mile Creek region. 



e. Paracyclas Virata. Found only in the Marcellus shales of Eighteen-mile Creek 

 region. 



f. Stropheodonta demissa is almost entirely restricted to the shales immediately 

 below the Encrinal limestone at Eighteen-mile creek. 



g. Strophalosia truncata is almost wholly confined to the Strophalosia or basal 

 Hamilton bed at Eighteen-mile creek. 



h. Many conodonts have been described from Eighteen-mile creek (see Gra- 

 bau 3). 





Thedford Region. 



Eighteen-mile 

 Creek. 







i 



h 



.2 8 



u 

 o 



W 



of 



« 



CO 



T3 

 t. * 

 03^ 



O 



03 

 ,£> 





 O 



a 



>> 



■""73 



03 



eg 

 O 



o 



9 



c3 od 



,c i 



03 "* 



co 



0, 



9 ^ 



a^ 



CO 



03 



co 



03 



& 

 O 



i 



a 



1—1 03 



"5 G 

 o 



a 

 S 



co' 

 9 



n 



co 

 O 



o 



CO 



o 



a 



CO 

 03 



O 



5 



Pisces : 



1. Aspidychthys notabilisf Whiteaves 



2. Ptyctodus calceolus Newb. and Worth . 



Trilobita : 



3. Phacops rana Green 



w 



? 













C 



? 



c 

 re 



C 



c 



C 



c 



c 



c 



c 

 r 



c 

 r 















S 







w 

 w 











r 









Phyllopoda : 



7. Elymocaris hindei Jones and Woodw . . 















