THE EGG-CAPSULE OF RAJA BINOCULATA GIRARD, 1854
The big skate (Raja binoculata Girard, 1854) lays probably the biggest egg-capsules in the Rajidae family. Descriptions and a picture of the egg-capsule of Raja binoculata are given by Cox (1963) and DeLacey & Chapman (1935). The last two authors measured twenty egg-capsules. They found ranges for the length from 265 to 305 mm and for the width from 110 to 140 mm.
The egg-capsules of Raja binoculata and Raja pulchra Liu, 1932 are at the moment the only ones known which can contain more than one egg inside. According to DeLacey & Chapman (1935) the egg-capsule of Raja binoculata has usually 3 or 4 eggs, but this can vary from 2 to 7 eggs. Ishiyama (1967:36) reports for Raja pulchra 1 to 5 eggs in an egg-capsule.
The egg-capsule of Raja pulchra is described and pictured by Ishiyama (1950, 1958, 1967). A drawing of the egg-capsules treated in Ishiyama (1950) is given below, the egg-capsule of Raja pulchra being in the lower row, second one on the left.
Ralph Cook sent me some pictures of an egg-capsule of Raja binoculata he found washed ashore on the Oregon coast. In these pictures you can clearly see the different eggs in the egg-capsule.
Ralph also found another egg-capsule of Raja binoculata on the beach on the Cove beach at Seaside (Oregon) on October 13th 2000, full with barnacles.
And here is a picture of an egg-capsule also found on the Oregon coast, on Januar 17th 2002 at Cannon beach, by Ingrid Bartels.
The egg-capsule was heavy, so Ingrid opened it to look inside: