Frequency - Word Form
  20 above
  20 analogous
  20 appear
  20 bloodless
  20 classes
  20 cord
  20 during
  20 efficient
  20 foetus
  20 front
  20 goes
  20 growing
  20 here
  20 means
  20 moving
  20 number
  20 work
  19 3
  19 besides
  19 concerned
  19 concoct
  19 discharged
  19 increase
  19 move
  19 movements
  19 necessity
  19 ovipara
  19 period
  19 point
  19 proportion
  18 back
  18 blood-vessels
  18 contribute
  18 corresponding
  18 deficiency
  18 ducts
  18 especially
  18 faculty
  18 gestation
  18 need
  18 next
  18 ought
  18 production
  18 second
  18 under
  18 useful
  18 weakness
  17 breath
  17 contributes
  17 differentiated
  17 differs
  17 hand
  17 happen
  17 high
  17 internal
  17 lower
  17 moreover
  17 organs
  17 produces
  17 reasonable
  17 reasons
  17 season
  17 secreted
  17 sex
  17 shed
  17 stage
  17 towards
  17 virtue
  16 complete
  16 differences
  16 distinction
  16 grey
  16 low
  16 mass
  16 mixture
  16 occurs
  16 quality
  16 secretions
  16 species
  16 superfluous
  16 testacea
  16 umbilical
  16 unless
  16 whenever
  16 wind-eggs
  15 act
  15 caused
  15 cephalopoda
  15 colours
  15 conception
  15 developed
  15 divided
  15 double
  15 fat
  15 formation
  15 good
  15 homogeneous
  15 live
  15 origin
  15 present
  15 product
  15 rate
  15 spoken