132 ANNALS NEW YORK ACADEMY OF SCIENCES 



small teeth on the anterior side and a few large teeth on the posterior. 

 Chondrophore probably present but not observed. Anterior and posterior scars 

 large. Probably two other smaller scars are situated near the hinge, one in 

 front of and the other behind the beak, between it and the anterior and pos- 

 terior scars. Pallial line apparently entire or with only an obscure sinus.' 

 Sculpture consisting of fine regular concentric striae. 



This type in general appearance is intermediate between Nucula and 

 Leda. From Nucula it differs in its transverse shape and produced an- 

 terior extremity. From Leda it differs in having the beak directed toward 

 the short side, which is probably posterior as in Nucula. The muscle 

 scars seem to be much as I have observed them in Leda bellistrista, but 

 there is no oblique internal ridge crossing the umbonal region, and the 

 arrangement of the teeth, chiefly to one side of the beak, is another con- 

 spicuous difference. This type also much resembles Paleoneilo, from 

 which it differs in lacking an external ligament and being without the 

 sinus, developed in the inferior contour and in the lines of sculpture. 

 The latest species which can with safety be referred to Paleoneilo occur 

 in the early Mississippian. Anthraconeilo differs from Yoldia in not 

 gaping behind and in having the beak directed toward the shorter side. 



In addition to the type species described beyond as Anthraconeilo taf- 

 fiana, there can probably be transferred to this group three species at 

 present included under Yoldia, viz: Y. carbonaria, Y. knoxensis and 

 Y. oweni. The two latter differ from Yoldia and agree with Anthraco- 

 neilo in having the beaks turned toward the short side of the shell, and 

 their inclusion in the latter is regarded as probably correct. The case of 

 Y. carbonaria is more doubtful, since it seems presumptuous to suppose 

 that so excellent a conchologist as Meek would assign to Yoldia a shell in 

 which the beaks pointed toward the short side, whereas, if they point 

 toward the long side, Y. carbonaria is clearly not a representative of 

 Anthraconeilo. Even if the beaks point toward the long side, however, 

 I should somewhat doubt the correctness of his reference to Yoldia, on 

 account of the convexity of the shell and the prominence of the beaks. 



Type species, Anthraconeilo taffiana. 



Anthraconeilo taffiana sp. nov. 



Shell rather large, transverse. Width nearly twice the height. Shape 

 subelliptical. Posterior end strongly and symmetrically rounded. Dorsal 

 border long, rectilinear. Ventral border convex, more strongly curved toward 

 the posterior end, subrectilinear anteriorly. Anterior end produced, more or 



7 If a sinus is really present, the orientation here employed should be reversed ; the 

 long side is posterior and the beaks point forward, toward the short side. 



