.M\1{^|.\\|| (;i;<ti.(>(ii('AL sruvKY 217 



r-Kiuis LUNUi.lTHS Lamarck. 

 J^l NLLITES IlEVERSA 11. pp. 



Date LX, Fi.rrp. 10, 20. 



]>cs(ri pi inn. — Z(i;iiMiiiii ll;ilii'll;iic ( |ici'liii|i> iii'i::iii;il I y di.-cciid oj- de- 

 pressed coiiicnl), zddccia >uli(|ii;itli;ii • |)cii1agonal, iisvially widest in the 



anterioi' \\;\\\'. arraiijj,ed in rather irregular radiating lines, ahout six in 2 

 mm., Willi an iiiii)ross('d line scjiarating the rows; ai'ca depix'ssed, its sur- 

 face gi'aiin-lincatc. Margin strongly raised, thick, and straight or 

 slightly concave across the ])osterior end and niiieli tliinner along the 

 sides, the anterior end appearing to he overlapped by the posterior ridge 

 of the next succeeding zooeciuin. Aperture surrounded hy a thickened 

 I'im, generally rounded in front and straighter hehind, sometimes siib- 

 (juadrate. its auterioi- Ijorder close to the prominent end of the next cell, 

 and the length and width averaging ahout half the corresponding dimen- 

 sions of the entire zooecium. 



Vibracular cells fusiform or elongate oval, rather large, one, usually 

 at each angle of junction between four zooecia. A constriction occurs 

 near the center of each, sometimes on one side only, at other times on 

 both. A narrow area may surround the opening. Under surface 

 marked by irregular depressed lines radiating from the narrow lower 

 extremity of the zoarium. Between these lines the surface is convex 

 and rather coarsely pitted and granulate. 



The only specimen seen is too imperfect to permit a positive declara- 

 tion that it is not a mere fragment of a discoid zoarium. Still, the 

 arrangement of the depressed lines on the lower surface does not look 

 right for a species in which the zooecia radiate from a center as in the 

 ordinary forms of Liniiilites. On the other hand this side looks de- 

 cidedly like d'Orbigny's figure of his Pavolunulifes elegans (Pal. Franc, 

 vol. V, pi. dccvi, fig. T), hence I expect to find that perfect specimens of 

 L. r&versa have a flabellate and not a discoid or conical form. 



Specifically^ L. reversa is distinguished from all species of Lunulites 

 known to the writer, except L. regidaris d'Orbign}', L. semilunaris 

 Marsson and L. paieTliformis Marsson, in having the posterior margin. 

 of the zooecium thicker and more premoinent than the anterior. From 

 the species mentioned it differs in the greater elevation and square out- 



