5io CRETACEOUS PALEONTOLOGY. 



lines parallel to the margin, and also by several varices of growth 

 at irregular intervals." (Whitfield.) 



Remarks. "This species somewhat approaches M. Julia Lea's 

 sp., but is not alate posteriorly as is that species, and the posterior 

 end is much more narrowly rounded. It also presents much the 

 appearance of the enlarged figures of Lithophagus infiatus herein 

 described, but is less cylindrical, being fuller or more convex on 

 the basal margin and the beaks are not so broad. It also holds 

 a different geological position." (Whitfield.) 



The dimensions of the type specimen are : length, 27 mm. ; 

 height, 14 mm. ; thickness, 15.5 mm. 



Formation and locality. Manasquan marl, Farmingdale 



(138). 

 Geographic distribution. New Jersey. 



Genus CRENELLA Brown. 



Crenella serica Conrad. 

 Plate LVL, Figs. 7-8. 



1860. Crenella (Stalagmium} serica Con., Jour. Acad. Nat. 



Sci. Phil., 2d ser., vol. 4, p. 281, pi. 46, fig. 23. 

 1 86 1. Crenella serica Gabb, Synop. Moll. Cret. Form., p. 169 



1864. Crenella (Stalagmium) sericea Meek, Check List Inv. 

 Foss. N. A., Cret. and Jur., p. n. 



Description. Shell small, the dimensions of an average indi- 

 vidual being: greatest length, 4 mm.; greatest width, 3 mm. 

 Oblique, subovate in outline, strongly convex, the umbo promi- 

 nent, the beaks incurved. The anterior slope from the umbo 

 abrupt, inflected towards the anterior extremity of the hinge- 

 line. Surface marked by fine, regular, concentric lines which 

 can be easily seen with the unaided eye, and by finer, regular, 

 radiating striae which can usually be seen only with a magni- 

 fying glass. 



Remarks. This beautiful little species, which has hitherto been 

 placed on record only from its original locality, Eufaula, Ala- 

 bama, occurs in New Jersey in the Marshalltown clay-marl and 



