Logan.] The Invertebrates, Niobrara Group. 495 



Although sometimes found singly, they are more often found 

 in groups. Adults often found with young attached to them by 

 their lower valves. Type specimens are adult forms united by 

 their entire lengths ; one of the specimens having three young 

 ones attached to it near its upper extremity by their lower 

 valves. 



Specimens of this mollusk were first observed by Doctor Wil- 

 liston in 1874 on the Saline river ; however, nothing but small 

 fragments were secured for the University collection until the 

 past summer, when a few specimens of a large lower valve were 

 obtained from Mr. M. R. Watson, of McCracken. A fragment 

 of another specimen was collected by Doctor Williston from 

 Niobrara outcrops on the Saline river in Ellis county. Other 

 forms belonging to the same species have been collected by Mr. 

 Allen, of Hays City. One of the specimens collected by Mr. 

 "Watson has Ostrea congesta adhering to the inner surface of the 

 valve. All other forms which I have seen were free from ad- 

 hering forms. 



Radiolites are not abundant in the Kansas fields. They oc- 

 cur at the base of the Ornithostoma beds just above the Fort 

 Hays limestone, and possibly in the upper surface of that for- 

 mation. None have been reported except from the south-cen- 

 tral portion of the Niobrara area in Trego, Gove and Ellis 

 counties. Collectors in looking for these shells will find it to 

 their advantage to follow the line of contact of the Fort Hays 

 limestone with the Ornithostoma beds. 



Parapliolas sphenoideus White. Plate xcix, fig. 12. 



Turnus sphenoideus White, 1876, Geol. Uinta Mts., p. 117. 



Parapholas sphenoideus White, 1879, Ann. Rep. U. S. Geol. Surv. for 1877, 



p. 300, pi. v, ff. la-d; Stanton, 1893, Bull. U. S. Geol. Surv. No. 106, 



p. 125, pi. xxvn, ff. 1, 2. 



Revised description: "Shell elongate, cuneate, inflated in 

 front, narrowed and laterally compressed behind ; beaks ante- 

 rior, incurved, adjacent; dorsal margins of the valves straight 

 and sloping from the beaks to the posterior end, capped or con- 

 nected by a slender, styliform, plain accessory plate ; posterior 



25 — iv 



