Apbil 14, 1916] 



SCIENCE 



533 



Smithsonian Institution from the so-called 

 Pamunkey of Maryland and Virginia, it be- 

 came perfectly evident to the writer that the 

 majority of the species were very similar to, 

 or identical with, the more common species 

 from the lower " Lignitic " or Bell's Landing 

 horizon of Alabama.^ Shortly afterwards he 

 observed other specimens while on a trip in 

 southern Virginia representing a higher " Sel- 

 Iceformis " horizon. All these faunas have 

 since been ably worked up by members of the 

 Maryland Geological Survey.^ 



Away to the northeast, but seemingly quite 

 in the general line of outcrop of the Maryland 

 Eocene, are the Shark Eiver beds with a poorly 

 preserved yet interesting fauna. Opinions of 

 Conrad, Cook, Heilprin and Clark have varied 

 as to whether these beds should be referred to 

 the horizon of the near-by Marylandian de- 

 posits or should be relegated to a still older 

 Eocene stage. The writer, however, has been 

 quoted on several occasions^ as believing that 

 the Shark River beds should be placed above 

 the general horizon of the Pamunkey Eocene, 

 within a Mid- or Upper Eocene stage. 



Since the data upon which this belief is 

 founded have not been made known, it seems 

 quite proper to place them on record that their 

 validity may be intelligently discussed. 



It may accordingly be noted: 



1. That the absence of such characteristic 

 Pamunkey species as Ostrea compressirostra, 

 Cucullma giganiea, Dosiniopsis leniicularls, 

 Crassaiella alceformis and huge Turritellce 

 and Venericardice seems to preclude the syn- 

 chronizing of the Pamunkey and Shark River 

 deposits. 



2. That the Shark River beds are not helow 

 the Pamunkey beds from : (a) The fact that if 

 they were they would naturally be the equiva- 

 lent of some basal or Midway Eocene horizon. 

 Certainly if such were the case there should 

 be some trace in the Shark River beds of that 

 great virile Midway fauna that stretches from 

 the Carolinas to the Rio Grande, on the north, 



1 A. J. S., Vol. 47, p. 301. 



2 See especially Eept. '01, Eocene. 



3 Men. 39, V. S. G. S., p. 17. 



and from Trinidad to east of Brazil, on the 

 south; the similarity should be as great be- 

 tween Shark River beds and Alabama Midway 

 as between Pamunkey and Bell's Landing beds 

 — in fact the " Lignitic " beds are more local 

 in character than the more truly marine Mid- 

 way. But the Pamunkey shows derivatives of 

 the Midwayan in its Hercoglossa, Cuculloece 

 and great Turritellce, while these striking 

 forms are absent from the Shark River de- 

 posits. (6) The fact that, as indicated above, 

 if these beds are pre-Pamunkey they must 

 also be pre-Midway, i. e., older than the oldest 

 known marine Eocene on this continent, which 

 seems quite out of the question. 



3. That the Shark Eiver beds are Mid-Upper 

 Eocene and above perhaps all of the Pamun- 

 key horizons from : (a) The fact that the gen- 

 eral aspect of the molluscan fauna is upper 

 and not lower Eocene. Witness the presence 

 of Aturia and not Hercoglossa; the large 

 rotund Caricellce closely allied to, if not iden- 

 tical with, the Claibornian forms showing 

 nothing in common with the small slender 

 Midway species; the Fusoficula of penita pro- 

 portions and appearance and not of the older 

 juvenis type; Turritellce of non-carinate, Clai- 

 bornian aspect; Pleurotomarice of huge di- 

 mensions as in the Upper Eocene beds of the 

 Carolinas though unknown in lower horizons; 

 Ostrece of the Claibornian divaricata (i. e., 

 sellceformis) type and with nothing in com- 

 mon with crenulimarginata of the Midway or 

 compressirostra of the Lignitic ; Pectens of the 

 types found in the Claiborne and Pope's Creek 

 beds, with no resemblance to those of earlier 

 horizons; Crassatellce of the high, huge alta 

 type of the Claibornian, with nothing in com- 

 mon with the lower Eocene forms; Voluti- 

 lithes, similar or identical with Claibornian 

 forms and without the Athleta characteristic 

 of the Lignitic. (b) The fact that the coral 

 from the Shark Eiver beds noted by Vaughan 

 is of a genus unknown from any other state 

 " from a horizon below the Claibornian." * 

 (c) The fact that although the vertebrate evi- 

 dence on this question is very slight, " Anchip- 



* Op. cit., p. 17. 



