590 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.59. 



Order TESTUDINATA. 

 Family PLEUROSTERNIDAE. 



GLYPTOPS CAELATUS Hay. 



There have been no additional discoveries of turtle remains in the 

 Arundel formation since Dr. O. P. Hay described 29 Glyptops caelatus 

 in 1908, so that our knowledge of this form rests entirely on the type, 

 a fragmentary specimen, from which little information can be obtained 

 as to its relationships to the other species of the genus. At my request 

 Doctor Hay was kind enough to reexamine the type materials for the 

 present study and reports as follows: 



T can not say whether Glyptops caelatus is more or less closely related to the Morrison 

 forms than to those from the Lower Cretaceous. In comparing the Morrison and 

 Arundel faunas I think I would not put G. caelatus in the balance. 



From the above statement it appears, therefore, on the highest 

 authority, that the Arundel turtle remains can not contribute any- 

 thing of value to the present discussion of this fauna. 



CLASS PISCES. 



At this time the known fish remains of the Arundel fauna consist 

 of a single scale of a Ganoid and a tooth which, in the sculpturing 

 of its flattened grinding surface, slightly resembles those of PtycJiodus 

 from the Niobrara formation of the Upper Cretaceous. It probably 

 represents an undescribed form. The specimen (Cat. No. 10294, 

 U.S.N.M.) was found by Mr. C. Englehart in 1894 near Contee, 

 Maryland. 



SUMMARY. 



In the preceding review of the several genera and species of fossil 

 vertebrates that comprise the known fauna of the Arundel formation 

 of Maryland, it is apparent that most of them were established on 

 very meager and, in some instances, inadequate materials. The 

 proper treatment of such more or less indeterminate forms has long 

 been one of the difficult problems in modern vertebrate paleontology- 

 In the handling of this fauna in the past, but little discrimination 

 has been made as to the adequate or inadequate nature of the speci- 

 mens on which the names were based. To regard all members of a 

 fauna as generically and specifically determinable, when from the 

 very character of the type specimens they can only be determined as 

 to order or family, is an erroneous practice. 



While in making up faunal lists it is necessary to include such 

 forms, it should always be specified to what extent such questionable 

 genera and species are determinable. , The neglect of such a precau- 

 tion has in the past sadly misled workers in their final conclusions 



so Fossil Turtles of North America, 1908, pp. 52, 53, pi. 7, figs. 1, 2. 



