How to plot rectangle/bounding box in R?

Question

How do I generate a box rather than the hourglass shape this code is returning? I've tried changing the order of the coordinates but always have that "x" forming rather than a box, sometimes as a sideways hourglass.

library(sp)
mybb <- cbind(x=c(363498.5,480497.5,363498.5, 480497.5,363498.5), y=c(5894630,5894630,5806524,5806524,5894630))
crs <-CRS("+proj=utm +zone=12 +datum=WGS84 +units=m +no_defs +ellps=WGS84 +towgs84=0,0,0")
mybb <- SpatialPolygons(list(Polygons(list(Polygon(mybb)),"1")), proj4string=crs)
plot(mybb)

Returns:

Answer 1

Not sure why rearranging the coordinates hasn't worked so far. This worked for me.

library(rgdal)
library(sp)

mybb <- cbind(x=c(363498.5, 480497.5, 480497.5, 363498.5), y=c(5894630, 5894630, 5806524, 5806524))
crs <-CRS("+proj=utm +zone=12 +datum=WGS84 +units=m +no_defs +ellps=WGS84 +towgs84=0,0,0")
mybb <- SpatialPolygons(list(Polygons(list(Polygon(mybb)),"1")), proj4string=crs)
plot(mybb)