Boros István (szerk.): A Magyar Természettudományi Múzeum évkönyve 5. (Budapest 1954)

Kolosváry, G.: On the known fossil Hydrozoa of Hungary

the Hydrozoa family tree of Vinassa de Regny, published at the beginning of the century, with the new, natural Hydrozoa system of All oit eau, issued in 1952, we come to the conclusion that the family tree of Vinassa must be put aside. — Vinassa took the Palaeozoic Stromatoporidae for a starting point (they being the ancient type), with many kinds of fossil Hydrozoa relegated to them at that time. Of this ancient type he takes out as separate main-branches Stoliczkaria and Spheractinia. This latter branch developed at the end of the Jurassic Hydractinia ; the branch Stoliczkaria produced Parkeria (perishing in the Cretacaeus), and the recent Ceratelladae group. The Hydrocorallia of today emerge without any oantecedent« from the ancient Palaeozoic group, on the family tree of Vinassa. — On the ground of above said facts, this tree is not valid any more. We have to design a new one, the more so as, owing to the latest results of the relevant investigations, the group Spongiomorphidae is also considered г. Hydrozoa. The new family tree,reproduced on Table III., shows that the order Labechioidea is the oldest. It becomes extinct at the'end of the Triassic but it is the first representative of the Hydrozoa in the Lower Silurian. Out of them the order of Stromatoporoidea must have branched, living till the end of the Jurassic, though its majority die out in the end of the Permian. Closely related to them are the Spongiomorphidae, with fossils known from the beginning of the Permian, disappearing at the end of the Triassic. These three orders represent the Palaeozoic ancient-types of Hydrozoa. The Mesozoic forms are the Spheractinoidea ; their connection to the former Palaeozoic types being very doubtful. The new type is represented by the Hydroidea. The Mesozoic types, becoming extinct at the end of the Createceous, are relieved by the Tertiary and more Recent forms. Generally therefore, the striated ancient structure type ascends to preponderance in Stromatomorpha, Spongiomorpha,Cylicopsis, Heptastylopsis, Heptastylis, Labechia, and Stromatopora, whilst the new specialization occurs in the groups Stylasterida, Axoporidae, Millepora and Hydractinia. On the fossil parents of these young forms, H. В о s с h m a published an excellent paper in 1951, and M. Lecompte also a paper in 1952. Systematical Summary A sketch of the most modern system is very important to have a clear and comprehensible view of our fossil Hydrozoas. Classis Hydrozoa Owen 1893. The five, also paleontologically known, orders are the following : Hydroidea Dana 1846; Spheractinoidea Kühn 1927; Labechioidea Kühn 1927; Stromatoporoidea Nicholson et Mûrie 1878; Spongiomorphida Alloiteau 1952. Hydroidea. — They present polyps and medusas. Solitary or colonies. Multiplication sexual and asexual. The structure of the colony is coenenchymatous-fibrous. Gastropora and dactylopora present. Periods : Cretaceous, Tertairy, and Holocene. Fam : Hydractinidae Agassiz 1862 ; Genera : Hydractinia van Beneden 1841, from the Eocene to the present days (its cenoman occurrence is dubious!) ; Kerunia Mayer-Eymar 1899, Eocene ; Cyclactinia Vinassa 1899, Italian Neogene and the Viennese Basin; Par actinia Vinassa 18Ö9, Pliocene; Delheidia Dollfus 1898, and Thalamospongia d'Orbigny 1850, Neocom. Fam.: Milleporidae M. Edwards 1869; tabulae present in gastropores and dactylopores. Structure not separated into horizontal lamellae, as the^ coenosteum is penetrated by irregulary winding channels. Genera : Millepora Linneus ; we find here, besides gastropora and dactylopora, also the В о s с h m a ampullae. From the Eocene* to Recent times ; Promillepora Dehorne 1920 and Balatonia Vinassa 1912, the latter differring more from the Stromatoporid type, and nearest to Milleporidium, yet not coincident with it. Promilleporae * Only : Millepora tornquisti Boschma 1951 !