MARYLAND GEOLOGICAL SURVEY 747 



the entire length of the tube, increasing slightly in prominence with the 

 growth of the shell; external sculpture absent, excepting for fine incre- 

 mental corrugations ; no trace of internal laminas detected. 



Dimensions. Longitude when straightened 23 mm., maximum diam- 

 eter 2.02 mm., minimum diameter 0.04 mm. 



Occurrence. KANCOCAS FORMATION. Noxontown Millpond, Delaware. 



Collection. Maryland Geological Survey. 



Genus HAMULUS Morton 

 [Morton, Syn. Org. Rem. Cret. Group, 1834, p. 73] 



Type. Hamulus onyx Morton. 



"Tubular, regular, involuted; volutions distinct; aperture circular." 

 Morton, 1834. 



A solitary form characterized by a falcate or involuted and frequently 

 alate tube, closed at the smaller end. The genus is apparently confined 

 to the Cretaceous. 



HAMULUS ONYX Morton. 



Hamulus onyx Morton, 1834, Syn. Org. Rem. Cret. Group, p. 73, ? pi. ii, fig. 



8; pi. xvi, fig. 5. 



Hamulus onyx Gabb, 1859, Cat. Inv. Fossils, Cret. Form., U. S. p. 1. 

 Hamulus squamosus Gabb, 1859, Ibidem, U. S. p. 1. 

 Hamulus squamosus Gabb, 1860, Jour. Acad. Nat. Sci., Phila., 2d ser., vol. 



iv, p. 398, pi. Ixviii, fig. 45. 



Description. " With six elevated, angular, longitudinal ribs extending 

 from base to apex. Length about an inch. The imperfect specimen 

 figured on plate ii was obtained by Dr. Blanding at Lynch's Creek, South 

 Carolina, in the green sand, and on a former occasion was supposed to be 

 a Dentalium. PI. xvi, fig. 5, however, represents the perfect shell from 

 the older cretaceous deposits at Erie, Alabama. I have a small individual 

 from Xew Jersey. It has never been found attached.'' Morton, 1834. 



Type Locality. Erie, Alabama. 



Hamulus squamosus was described by Gabb as "very closely allied to 

 H. onyx, but differing in having a strongly marked raphe, which nearly 

 doubles the width of the shell." Apparently Gabb's species was described 

 from a young form, while Morton's H. onyx represents the normal adult. 



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