702 A CENTURY OF PROGRESS IN THE NATURAL SCIENCES 



published by James Hall and J. M. Clarke (1898). These sponges are particu- 

 larly abundant in the Devonian of New York State. In 1842 T. A. Conrad de- 

 scribed and named Hydnoceras tuberosum and considered it a cephalopod. Lard- 

 ner Vanuxem described TJphantaenia chemungensis as a marine plant. Another 

 closely allied form was called Dictyophyton, revealing these authors' concept of 

 its place in the classification. Many diverse forms were described before 1880 

 but the conditions of preservation made recognition of their real nature difficult. 

 The internal and external casts of their bodies left distinct impressions of their 

 spicular network. Similar fossils from Crawfordsville, Indiana, yielded more 

 definite evidence and led to a recognition of their relationship to the living reti- 

 culate silicious sponges represented by Euplectella aspergiUum. 



A group of Cambrian sponges of the class Pleospongia were investigated in 

 great detail by Vladimir J. Okulitch (1943). His classification is based on their 

 morphology, affinities, and distribution. The first representatives of this class 

 were described in 1861 by E. Billings of Canada as Archaeocyathus from the 

 Lower Cambrian of Labrador. Okulitch 's classification consists of 5 subclasses, 

 11 orders, 20 families, and 89 genera. Previous to the appearance of this work 

 the Pleospongia were variously grouped with the Foraminifera, Sponges, or 

 Corals. Okulitch concludes that they represent a separate class of the Porifera 

 which became extinct in the Upper Cambrian, that there are no links between 

 the Silicispongia and Calcispongia, and that they should be regarded "as inde- 

 pendent branches having a common ancestor in the Pre-Cambrian." 



Coelenterata: The Coelenterata is a phylum more advanced than the sponges 

 and consists of a large number of extinct and living species. They are repre- 

 sented in the fossil record from the Cambrian to the Eecent. At present they are 

 usually divided into the following groups: Ilydrozoa, Stromatoporoidea, Grap- 

 tozoa, Scyphozoa, and Anthozoa. Many genera and species of corals, both liv- 

 ing and fossil, were described in the first decades of the nineteenth century but 

 the organization of their morphological features was not well known. Among 

 the earlier authors were Lamarck, Ehrenberg, and Goldfuss. Thorough investi- 

 gations of living corals were made by ]\Iilne-Edwards and Haime. These were 

 followed by special studies of particular groups of fossil forms, with special at- 

 tention to the morphology and structure of the polyps and the occurrence and 

 distribution of fossil faunas through geologic time, culminating in the Histoire 

 natureUe des coraUaires (1857-1860). The classification of Milne-Edwards and 

 Haime is based on the differences in the septa and the methods by which new 

 ones are produced. The subdivisions are based on the number of tentacles. 



During the middle of the nineteenth century many papers, largely of a de- 

 scriptive nature, were published, among the more important of which were those 

 by Reuss, Fromentel, Hall, and Duncan. Differences in the method by means of 

 which new septa originated in the Paleozoic Tetracoralla as compared to those 

 of the Hexacoralla and Octocoralla were described by Kunth in 1869-1870. 

 Thin sections made from the calcareous skeletons were subjected to microscopic 

 analysis. A similar method of study was used also by Pratz and Koch with ac- 

 companying illustrations in their published work. In 1896 Maria Ogilvie investi- 

 gated fossil and living anthozoans and presented her interpretations of the phy- 

 logenetic relationships of the Tetracoralla and Hexacoralla. Moseley (1877) in 

 a study of MiUepora showed the relation of Stromatoporans to certain Hydrozoa 



