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New Zealand Echinoderms.
Turning now to the New Zealand echinoderm fauna, I select, the ophiuroids for particular mention, as I have had opportunities for personal study of these forms in recent years.
Mortensen showed in 1924 that at least six New Zealand ophiuroids are viviparouis. All of these lack a free-swimming larva and have a more or less direct development. In the case of Ophiomyxa brevirima direct evidence has been produced that this is so (Fell, 1940 a). In addition it has been shown that the oviparous form known as “Kirk's ophiuroid” has an absolutely direct development. I have also described the large, yolky egg of Pectinura maculata which indicates a direct development (1941). Other species provide some indication as to the nature of their development from the size of their eggs (see section of this paper on the egg).
The following ophiuroids are known, or are believed to have direct development:—
| Ophiomyxa brevirima | Pectinura gracilis |
| Amphiura magellanica | Pectinura maculata |
| Amphiura annulifera | Amphiocnida pilosa |
| Amphiura praefecta | Amphioplus basilicus |
| Amphipholis squamata | Kirk's ophiuroid |
| Pectinura cylindrica | Ophiozonoida picta |
In addition Mortensen (1924) has given reasons for believing that Amphiura hinemoae may have direct or shortened development.
New Zealand ophiuroids whose development is known or believed to be of the indirect pelagic type are:—
| Ophiocoma bollonsi | Amphiura amokurae |
| Ophiactis resiliens | Amphiura alba |
| Amphiura spinipes | Ophionereis fasciata |
| Amphiura rosea |
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The development of the remaining twenty-three species is unknown.
The above tables show that out of nineteen ophiuroids of New Zealand of whose development we have any knowledge at all, twelve—i.e., 63%, are believed to have direct development, and only seven, or 37%, to have indirect pelagic development. Thus, the proportion of ophiuroids believed to have direct development is much higher in New Zealand waters than in those of Britain (and Europe).