22 Hill — PalcijulohMiij of the Trlnitij Division. 



The Serpulas have such wide ,<2;eol(\!4ic range and .so few s]>ecifie 

 characters that they are of little value in geologic diagnosis. 



Occurs at gypsum bluffs of the Little INIissouri, and in great 

 abundance at the plant bed near Glen Rose, and also throughout 

 the extent of the lower fossiliferous Glen Rose beds in Texas. 



MoLLUSCOIDEA. 



Genus indeterminate. 



Microscopic oval cells al)Out one millimeter in length, growing 

 in colonies attached to shell o^Serpahi palax.iciiMS and other forms ; 

 cells not overlapping, but in close contact with^3acll other, form- 

 ing a single layer of delicate net-work. 



The cells of this species have not the jjyriform shape or im- 

 bricated arrangement of Menihranhponi or the vibracular cells of 

 Lnnulltes, and hence are assigned to no generic position at pres- 

 ent. This form is the only one belonging to this order yet found 

 in these beds. It occurs attached to other shells in the beds of 

 the plant locality on the Paluxy near Glen Rose, Texas, at the 

 base of the Glen Rose beds. 



MOLLUSCA. 



Anomia texana np. uov. 



Plate I, Fig. 5. 



Anoiniji sp. indet. Hill. Arkansas Geological Surve}^, Annual 

 Rei)ort 1888, vol. ii, p. 135. 



Thin, discoidal, indistinguishable specifically from many spe- 

 cies of this genus; right or lower valve attached, concentrically 

 laminated; left Uj)per valve arched and very irregular ; seldom 

 exceeds one-half inch in greatest diameter. 



This species al>ounds in the earliest fossiliferous horizon of 

 the Trinity Division, such as the beds in Paluxy creek, west of 

 Glen Rose, and at the gypsum l)lufrs of the Little Missouri, in 

 Pike county, Arkansas. It also occurs in most of the localities 

 throughout the extent of the Glen Rose beds. 



