FROM THE TERTIARY OF VIRGINIA. 233 



FAMILY SERPULID^E. 



GENUS SERPULA. 

 S. CONVOLUTA, PL. 34. FIG. 1. 



S. testa in spiram discoidalem contortd, tenui, plerumque cancellatd, apud apicem regulariter valuta; aperturd rotunda. 

 Shell twisted into a discoidal spire, thin, usually cancellate, regularly whorled near the apex; mouth round. 



Diam. .10 of an inch. 



Remarks. This shell is generally twisted into a regular disc. The sculpture is very 

 variable, sometimes seeming like longitudinal moniliferous costse, and, at others, regu- 

 larly cancellate. The apex is singularly formed, being smooth and perfectly voluted, 

 like a young Turbo. This is, I suppose, the form it has when excluded from the egg. 



S. ANGUINA, PL. 34. FIG. 2. 



S. testa minima, irregulariter contortd, striatd, crassa; striis irregularibus transversis; apertura rotunda. 

 Shell very small, irregularly twisted, striate, thick; striae irregular, transverse; mouth round. 



Diam. .04 of an inch. 



Remarks. This is a very minute species, and is, I believe, the only one of our fossil 

 Serpulee that has no longitudinal lines on the surface. This character will readily dis- 

 tinguish it from others. The apex has the same voluted character as the last, although 

 not as well developed. 



GENUS PETALOCONCHUS,* (Nosis.) 



Testa tubularis, solida, irregulariter contorta, laminis longitudinalibus duabus internis. 

 Shell tubular, solid, irregularly twisted, with two internal longitudinal plates. 



Remarks. The singular shell, on \yhich I propose to found the above genus, differs 

 from all the known tubular shells that I have met with, in the two internal longitudinal 

 plates. It may possibly belong to the family Scalaridae, and, if so, presents a link be- 

 tween them and the Plicacidse. 



P. SCULPTURATUS, PL. 34. FIG. 3. 



P. testa vel contortd vel turritd, crassa, costulis longitudinalibus noduliferis; laminis internis politis, lavibus, ad aper- 

 turam obsoletis; aperturd rotunda. 



Shell sometimes twisted, sometimes turrited, thick, with small longitudinal noduliferous ribs; internal lamina 

 smooth, polished, obsolete at the mouth; mouth round. 



Diam. .20 of an inch. 



Remarks. The longitudinal costse are generally nodulous, but they occasionally seem 

 rather to be cancellated by transverse sulci, which, in other specimens, appear to usurp 

 their place. The two internal laminae are placed at about one-sixth of the circumference 

 apart. They are generally directed towards the centre, and sometimes nearly meet. In 

 some specimens they are much smaller than in others. They rarely or never seem to 

 be continued to the aperture. 



This is a very variable shell, both as to the sculpture and internal plates. I at first 



* A Ttifo&w, lamina, et xoy^oj, concha. 



VOL. IX. 62 



