Lattice PDF two polygon maps per page - help

I would like to print two polygon maps per
PDF page. The following code prints each
map on two PDF pages. The maps are small
enough to print two on one page.

MY QUESTION. How can I get these two polygon
maps to print on ONE PAGE?

I have Deepayan Sarkar's "Lattice Multivariate
Data Visulaization with R" book and want to
do a polygon display like the graphs in Figure
1.2.

Using R 2.8.1 latest updates on Windows XP

CODE FRAGMENT FOLLOWS:

pdf(file = "myoutputfile.pdf", width=7, height=10)

library(lattice)                    
trellis.par.set(sp.theme())         

spplot(tx3_sp, c("D_PCT"),
    colorkey=list(height=1.0, width=0.6),
    main = list(label="My first title",cex=.5),
    line=0,
    sp.layout = list("sp.text",coordinates(tx3_sp),
    as.character(tx3_sp$PCT,cex=.02),
    as.table = TRUE)
 )
spplot(tx3_sp, c("D_TOT"),
    colorkey=list(height=1.0, width=0.6),
    main = list(label="My second title",cex=.5),
    line=0,
    sp.layout = list("sp.text",coordinates(tx3_sp),
    as.character(tx3_sp$PCT, cex=.02),
    as.table = TRUE),
    newpage = FALSE
 )
dev.off()

Thanks in advance for your suggestions!
Jim Burke