NO. lO AMERICAN SPECIES OF LEPIDOCYCLINA VAUGIIAN 29 



LEPIDOCYCLINA (NEPHROLEPIDINA) SEMMESI 

 Vaughan and Cole, n. sp. 



Plate IS, figs. 3-5; plate 30, fig. i ; plate 31, figs, i, la; plate 32, figs. 2, 3 



1930. Lcpidocyclina ocalana Nuttall, Journ. Pal., vol. 4, p. 2^2 («o< Cushman). 



Test of medium size, very slightly selHform, a small umbo, more 

 developed on one side than the other. The diameter of the megalo- 

 spheric individuals ranges from 9 to 14 mm, thickness from 1.4 to 2.5 

 mm ; microspheric individuals attain a diameter of 20 mm or more, 

 with a thickness of about 4.5 mm. The surface is flaky, vermiculate- 

 scrobiculate, with numerous small papillae, which are most prominent 

 on the umbo. 



The embryonic chambers are of nephrolepidine type, a larger 

 chamber embracing a slightly smaller one. The chamber wall is thick. 

 The width of the two chambers, measured in a slightly oblique section, 

 is approximately 0.69 mm. The smaller chamber has a length of 

 0.51 mm and a width of 0.38 mm. The chamber wall is 0.06 mm in 

 thickness. 



The equatorial chambers are of two types, short-spatulate near 

 the center, grading outward into arcuate chambers. The spatulate 

 chambers commonly are about 100 ju, in radial diameter and about 90 /x 

 in transverse diameter. The arcuate chambers are about 60 /x in 

 radial diameter and about 120 ju in transverse diameter. 



The lateral chambers vary in number from about 8 on each side of 

 the equatorial layer at the center in megalospheric individuals to as 

 many as 25 in microspheric individuals. Some of the chambers are 

 arranged in regular tiers, but most are irregularly spaced and over- 

 lapping. The chamber floors are much thickened in the layers adjacent 

 to the equatorial layer, the chamber cavities showing only as narrow 

 slits. The peripheral layers have large, open chambers which vary in 

 length from 150 to 275 ,/x ; their height being about 45 jj. The 

 equatorial chambers have a height at the center of about 100 /x ; at the 

 periphery about 290 /x. 



The pillars are pronounced, but irregularly developed. They com- 

 monly do not extend to the surface of the test. Some branch to form 

 two or more pillars that extend separately to the surface. Diameter 

 of the pillars variable, ranging from 75 jx to as much as 300 jjl ; average 

 about 150 jx. 



Localities and (jcologic Jioricon. — The cotypes are from locality 

 MioOV, 0.6 km southwest of Dos Caminos, near Tantoyuca, State of 

 Vera Cruz, Alexico, collected by T. W. A^aughan and D. R. Semmes : 

 also collected by D. R. Semmes near Tamemas, in the Tantoyuca 

 district at the west end of the second east- west hill north of Peregrino. 



