i8i Midway Stage 67 



Localities. — Alabama: Black Bluff, Tonibigbee river; Mat- 

 thews' Landing, Alabama river (Fig'd type); 

 I mi. N. of Midway (horizon of bed 18, sect. p. 

 31). 



MERE TR IX. 



Meretrix ripleyana, PI. 6, fig. 6. 



Syn. Venus ripleya?ia Gabb, Jr. Nat. Sci , Phila., vol. iv, 

 i860, p. 393, pi. 68, fig. 22. 



Gabb' s original description. — "Inequilateral; beaks small, ante- 

 rior; cardinal margin strongly curved, anterior semicircular, basal 

 and posterior regularly rounded, surface marked with regular 

 transverse ribs. 



'' Dimensiojis. — Length .55 in., width .7 in., diameter .38 in. 



'"Locality. — Ripley group, Hardeman Co., Tenn. Prof. Saf- 

 ford." 



Nearl}^ all the type specimens of this species were from a clay 

 bank 2 miles S. S. E. of Middleton, Tenn. One specimen, how- 

 ever, is from 2 miles E. of Middleton, and another is from the 

 limestone on Muddy creek. The specimen that Gabb used in 

 his description and which he figured is probably the one now 

 represented by the blue clay filling, the shell having been ex- 

 foliated. However, several other fairly well preserved specimens 

 show the character of the species. One is figured herewith. 

 This is perhaps not quite so elongated as the majority of the 

 specimens; there seems to be considerable variability in this 

 regard. The concentric rugae are fairly strong and regular from 

 the middle of the valve downwards, while upwards towards the 

 beaks the shell is nearly smooth. All the specimens from Dr. 

 Safford are approximately the same. The lunule is rather nar- 

 row and long, giving that margin of the shell an unusual 

 straightness from the umbo to the anterior end. 



In Georgia casts of this species occur at the very base of the 

 Midway on the Chattahoochee river, and thence to the mouth of 

 Sandy creek. Another slightly larger variety occurs in the cuts 

 north of Snow Hill, off-set of the section on p. 31; 



Fig. 7 is from Huddleston's, 3 miles W. of Crainesville, Tenn. 

 The same form occurs in U. S. Nat. Museum material brought 

 from 4 miles N. E. of Kemp, Kaufman Co. , Texas. 



Meretidx sp. 



While at work on the Arkansas and Texas State Surveys, the 

 writer frequently found casts of this genus in the Midway lime- 



