THE reduction in size of the cœlom in the genus Notopterus has resulted in certain interesting modifications of the alimentary canal, swim-bladder, kidneys and gonads. An anomalous feature has ...
The ovaries are large and eggs are much larger than other mammals with large amounts of yolk. Ova released into coelom and picked up by the infundibulum -> oviduct, where fertilization takes place -> ...
The rest of the membrane is usually rather lightly skeletalised, with small platelets only. Echinoids other than cidaroids have soft-tissue sacs that are external extensions of the internal coelom.