1 82 Bulletin 31 182 



Verticordia eocensis Langdon, PL 55, Figs. 13-16 



F. eorensjs hangdon, Amer. Jour. Sci., voL 41,1886, p. 20S. PL 6, 



fig. 13, Ala. GeoL Surv.,Bul]. i.— Aldrich. 

 Not V. eocoene^isis Cossmann, Notes CompL, 1893, p. 7, pL i, fig. 6 



from Jackson, Miss. 

 V. eocenensis Ball, pa/iiin, Trans. Wag., Ill, 1903, p. 1510. 



Lanodon's original description.— ^\\^\\ rotund, beak recurved, ele- 

 vated and striate, substance of the shell rather thick, lunule obscure, one 

 prominent cardinal tooth, lateral teeth oblique, margin dentate and crenu- 

 lated between dentitions ; nacre brilliantly pearl)' ; muscular^impressions 

 two, profound ; pallial line obscure ; closelj- ribbed ; ribs about 16, crenu- 

 late, radiating regularly from the beak and slightly recurved. 



Length .25, Breadth .25, Height .06. 



This, I believe, is the first I'eriicordia described from the Eocene, 

 there having been only three species known among living and fossil shells, 

 two of these being Miocene. Differs from W einmonsi Con., in being ro- 

 tund and having more ribs, and from V, cardiifonnis Wood in having no 

 .striations between the ribs, in being more rotund, and showing no incurv- 

 ing of the ribs as they approach the ventral margin. 



Claiborne, Ala., and Jackson, Miss. 



In the typical form eocensis there is not much abrupt varia- 

 tion in the spacing or size of the ribs. However, a Httle irregu- 

 laritj' is noticeable in about the third or fourth from the posterior 

 margin. 



In our specimens from Hickorj^ and the Sabine River, from 

 the St. Maurice horizon, the tendency to irregularity becomes 

 more noticeable. There are three posterior ribs, then a rather 

 broad space, then two ribs slightly closer together followed by 

 about eleven quite evenly spaced. 



In the form described by Aldrich as sotoensis (The Nautilus; 

 vol. 16, 1902, p. 100, pi. 4, figs. 19-21) there are two posterior 

 ribs, then a space, anterior to which there are twelve ribs (see 

 pi. 55, figs. 10-12). 



For the reader's convenience we here include Aldrich' s de- 

 scription of sotoensis : 



Shell small, strongly ribbed with twelve ribs, then a blank space, 

 then two ribs near the margin, beaks blunt and rounded, ventral margin 

 serrated ; internal tooth long and curved. Interior verj' porcellaneous ; 

 muscular scars slightly impressed. 



