Weller — Kinderhook Faunal Studies. 



181 



Orthothetes inflatus (W. & W.). 



PI. XVI. f. 2-3. 



The types of this species are from both the oolite bed and 

 the base of the superjacent brown magnesian limestone. The 

 most perfect specimen among the types is from the upper 

 bed, and a description of the species is given with the descrip- 

 tion of the fauna from that horizon (see p. 195), although 

 the species is probably more common in the oolite. 



Orthothetes sp. undet. 



PI. XVI. f. 1 . 



Associated with 0. inflatus in the oolite bed there is another 

 form of the genus Orthothetes which may prove to be a dis- 

 tinct species. It differs from 0. inflatus in having the great- 

 est convexity of the brachial valve much nearer the front (A) 

 of the shell, as is shown in the accompanying profile outlines. 



Specimens of this form are often larger than the typical 0. 

 inflatus^ but not sufficient material has been in hand for study 

 to determine whether or not the larger size of the adult shells 

 is a constant characteristic. No pedicle valves, which can be 

 definitely correlated with this type of brachial valve, have been 

 observed. 



Rhipidomella burlingtonensis (Hall). 



PI. XVI. f. 6. 



The specimens in the oolite bed which have been identified 

 with this species, differ from the normal form of the species 

 on account of their much smaller size, as is shown in the 



