no. 2359. AN OPERCULATE SERPULA—WADE. 43 



SYSTEMATIC DESCRIPTIONS. 



Class ANNELIDA. 



Order POLYCHAETA. 



Suborder TUBICOLA. 



Family SERPULIDAE. 



Genus HAMULUS Morton. 



Hamulus Morton, Syn. Org. Rem. Cret. Group, 1834, p. ~>?>. 



Type. — Hamulus onyx Morton. 



"Tubular, regular, involuted; volutions distinct; aperture circu- 

 lar." Morton, 1834. 



Tubes with from three to seven axial ribs; larval or early stages 

 attached, usually broken away and solitary in the adult; nuclear shell 

 portions circular and often triangular in cross section; inner surface 

 of the tubes smooth; operculum calcareous, consisting of a circular 

 anterior disk with a three-cornered, elongate posterior process or 

 apophyse. 



HAMULUS ONYX Morton. 



Plate 9, figs. 1, 2, 3, 5, 6. 



Hamulus onyx Morton, 1834, Syn. Org. Rem. Group, p. 73, pi. 2, fig. 8; pi. 16, 

 fig. 5. — Gabb, 1859, Cat. Inv. Fossils. Cret. Form. U. S., p. 1. — Stephenson, 

 1914, U. S. Geol. Surv. Prof. Paper 81, p. 24, tables 2, 8.— Gardner, 1916, 

 Md. Geol. Sur. Upper Cret., p. 747 (part). 



Description. — "With six elevated, angular, longitudinal ribs ex- 

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

 specimen figured on Plate II was obtained by Dr. Blanding at 

 Lynchs Creek, South Carolina, in the green sand, and on a former 

 occasion was supposed to be a Dentalium. Plate XVI, figure 5, how- 

 ever, represents the perfect shell from the older Cretaceous deposits 

 of Erie, Alabama. I have a small individual from New Jersey. It 

 has never been found attached.'' Morton, 1834. 



Type locality. — Erie, Alabama. 



Tube small, compact, and rather strong; in form a very elongate, 

 gently curved, ribbed, or corrugated cone; shell of tube made up of 

 two layers — an inner layer of lamellar calcareous material, and an 

 outer layer of chitinous calcareous material bearing the external sculp- 

 ture; nucleus or protoconch unknown, tube attached to some for- 

 eign object during nuclear stage; external sculpture consisting of 

 six prominent axial ribs and sulci; transverse or incremental lines 

 fine and very numerous in some individuals, quite obscure in other 

 individuals; internal surface smooth; aperture circular; apertuarl 



