VERMES. 309 



Description. — Shell usually discoid and flattened, attached by 

 the initial po'rtion of the tube only, with three or four subquad- 

 rangnilar volutions in contact throughout except rarely for a 

 short distance near the aperture; the initial portion of the tube, 

 at the point of attachment is somewhat irregular, the outer 

 volutions much more regular, codling either dextrally or sinis- 

 trally; the side opposite the point of attachment more or less 

 umbilicate. The periphery of the shell bicarinate, the sides of 

 the volutions with a broad, shallow, rounded, longitudinal de- 

 pression or furrow. Aperture subcircular, although the external 

 outline of the tube is quadrangular, due to the thickening of the 

 shell at the corners. 



The dimensions of a rather large individual are: diameter, 

 9 mm.; thickness, 1.2 mm. 



Remarks. — This little spirally coiled worm tube is not un- 

 common in the Vincentown limesand. It usually occurs entirely 

 free, although the side by which it has been attached may always 

 be recognized by the fracturing of the initial portion of the shell. 

 All those specimens which have been observed attached to other 

 objects, have been attached to various species of bryozoans. The 

 tubes are coiled indifferently to the right or to the left from the 

 point of attachment, the numbers of sinistral and dextral indi- 

 viduals being about equal. 



Formation and locality. — Vincentown limesand, Vincentown. 

 (154), Medford (161), near Hurffville (170). 



Geographic distribution. — New Jersey. 



Genus Hamulus Morton. 

 Hamulus falcatus (Coarad). 



Plate XXII., Figs. 11-12. 



1869. Dentaliimi falcatum Con., Am. Jour. Conch., vol. 5, p. 44, 



pi. I, figs. 12 and 16. 



1870. Palcula hafimtus Con., Am. Jour. Conch., vol. 6, p. 77. 

 1892. Dentalium (Falcula) falcatum Whitf., Pal. N. J., vol. 2 



(Monog. U. S. G. S., vol. 18), p. 169, pi. 20, figs. 12-18. 

 1905. Hamulus falcatus Johns., Proc. Acad. Nat. Sci. Phil., 

 1905, P- 5- 



