3IO CRETACEOUS PALEONTOLOGY. 



Description. — Internal casts small, cylindrical, gradually taper- 

 ing and strongly curved with a decreasing curvature as they 

 increase in size, the smaller extremity being much more curved 

 than the larger parts. 



The dimensions oi an average individual are : length of tube,. 

 28 mm. ; larger diameter, 2.8 mm. ; smaller diameter, i.i mm. 



Remarks. — This species is known only from internal casts, and 

 is quite probably not distinct from H. sqiiamwsus Gabb,^ an 

 Alabama species described from the shell itself. A single indi- 

 vidual from the Marshalltown clay-marl has been observed upon 

 which a portion of the shell is preserved, which shows the same 

 longitudinal folds present in the Alabama specimens. 



Formation and locality. — ^Marshalltown clay-marl, near Swe- 

 desboro (177) ; Navesink marl, various localities. 



Geographic distribution. — New Jersey, Alabama. 



Hamulus lineatus n. sp. 

 Plate XIX., Pig. 7. 



Description. — Internal casts of tubes cylindrical, nearly straight 

 or slightly curved, smooth, increasing very gradually in size. 



The dimension oif a nearly straight specimen, probably incom- 

 plete, are: length, 53 mm.; greater diameter, 3.6 mm.; lesser 

 diameter, 2.5 mm. 



Remarks. — The specimens to which this name is here applied are 

 the casts of certain more or less straight tubes found commonly 

 in the Merchantville and Navesink formations. In hand specimens 

 these objects are not unlike casts of burrows of habitation of some 

 annelid worm, but unlike such burrows they lie parallel with the 

 bedding of the strata and not vertical to it. No trace of the shell 

 substance itself, of the tubes, has been observed, the specimens 

 being identical in lithologic character with the numerous internal 

 casts of gastropods with which they are associated. Some of the 

 individuals resemble the internal casts of Dciitalium arena turn, 

 but they taper less rapidly than that species, and are straighter or 

 less regularly arcuate. 



"Jour. Acad. Nat. Sci. Phil., 2d ser., vol. 4, p. 398, pi. 68, fig. 45 (i860). 



