"dolphins" <-
structure(list(wt = c(35, 42, 71, 65, 63, 64, 45, 54, 59, 50, 
42, 55, 37, 47, 40, 52), heart = c(245, 255, 525, 425, 425, 440, 
350, 300, 350, 320, 240, 305, 220, 310, 210, 350), logweight = c(3.55534806148941, 
3.73766961828337, 4.26267987704132, 4.17438726989564, 4.14313472639153, 
4.15888308335967, 3.80666248977032, 3.98898404656427, 4.07753744390572, 
3.91202300542815, 3.73766961828337, 4.00733318523247, 3.61091791264422, 
3.85014760171006, 3.68887945411394, 3.95124371858143), logheart = c(5.50125821054473, 
5.54126354515843, 6.26339826259162, 6.05208916892442, 6.05208916892442, 
6.0867747269123, 5.85793315448346, 5.7037824746562, 5.85793315448346, 
5.76832099579377, 5.48063892334199, 5.72031177660741, 5.39362754635236, 
5.73657229747919, 5.34710753071747, 5.85793315448346), species = c("styx", 
"styx", "styx", "styx", "styx", "styx", "styx", "delph", "delph", 
"delph", "delph", "delph", "delph", "delph", "delph", "delph"
)), .Names = c("wt", "heart", "logweight", "logheart", "species"
), row.names = c("1", "2", "3", "4", "5", "6", "7", "8", "9", 
"10", "11", "12", "13", "14", "15", "16"), class = "data.frame")