MOLLUSCA. 493 



1886. Radula reticulata Whitf., Pal. N. J., vol. i (Monog. U. 

 S. G. S., vol. 9), p. 63, pi. 9, fig's. 8-9. 



Description. "Shell small, moderately oblique, strongly 

 ovate and inflated. Hinge short; beaks proportionately strong 

 and projecting beyond the cardinal line. Valves nearly equal; 

 anterior margin straight and not at all gaping; auriculations 

 small but distinct, rectangular or very slightly pointed at their 

 outer angles, Surface radiately ribbed, those of the anterior 

 and posterior slopes faintly marked or obsolete, ribs (about 

 30) distinct, with five or more indistinct on each side; sub- 

 angular on the middle of the valves and rounded toward the 

 sides, crenulate or subspinose on the larger specimens when well 

 preserved, but often appearing nearly smooth. Entire surface 

 marked by concentric lines which give a roughened surface when 

 perfect, giving the reticulated character indicated by the specific 

 name." (Whitfield.) 



Remarks. This species is frequently associated with L. pelag- 

 ica, but it can always be distinguished from it by reason of its 

 smaller size and its much finer plications. The specimens are 

 usually preserved in the form of internal casts so that the deli- 

 cate concentric surface markings cannot be detected, but upon 

 some specimens from the Marshalltown marl near Swedes- 

 boro the shell is perfectly preserved. Whitfield has considered 

 Lima denticulicosta Gabb as a synonym of L. reticulata. In this 

 he is probably in error, since that species is described as having 

 "about 28 ribs," while usually as many as 40 may be easily rec- 

 ognized upon specimens of R. reticulata, and furthermore the 

 surface markings are very different in the two species. 



The specimens from New Jersey, which have sometimes been 

 identified as Radula acutilineata, are probably members of this 

 species. No specimens agreeing with typical individuals of L. 

 acutilineata have come under the observation of the writer dur- 

 ing the prosecution of the present work. 



Formation and locality. Merchantville clay-marl, near Mat- 

 awan (101), Lenola (163); Marshalltown clay-marl, near 

 Swedesboro (177); Wenonah sand, near Crawfords Corner 

 (i26 3 ); Navesink marl, Atlantic Highlands (108), near Red 



