REVISION OF PALEOZOIC STELLEROIDEA. 29 



reason why they occur less frequently in limestones is partially 

 accounted for by the fact that during the weathering process they 

 are almost always ruined. Those found in such deposits nearly 

 always occur in the thin shale partings between the bedded limestones. 

 In coarse sandstones they are less often seen, probably because these 

 sediments are so much moved by the storm waves action that 

 destroys the skeleton by separating the plates. Unless a starfish 

 is quickly covered by sediment it is sure to be broken up and jumbled 

 into a mass of unrelated ossicles, because the skeletal parts are rarely 

 coossified. Hence the best preserved specimens are found in mud- 

 stones and especially in the fine-grained, somewhat muddy sand- 

 stones. Here they usually occur as fine molds, since all of the calcium 

 carbonate has been dissolved out by the atmospheric waters. Such 

 material is apt to be fairly abundant in individuals, and although a 

 little difficult to study is often well preserved. Its interpretation is 

 dependent on artificial casts or squeezes in wax or gutta-percha. 

 When found in black slates, as at Bundenbach, the skeleton is pre- 

 served in iron pyrite, and even though these sediments have been 

 subjected to mountain making, the specimens can be cleaned me- 

 chanically of the adhering slate. The process is, however, a laborious 

 one and has been successfully used only by Stiirtz and his two prep- 

 arators. In the calcareous shales asterids are often well preserved, 

 with the original skeleton more or less permineralized and the ossicles 

 cemented together so that parts of the individuals weather out as 

 free fossils. This is particularly the case in the Bichmondian deposits 

 of Ohio and Indiana. 



As a rule, starfishes are obtained in single specimens and as acci- 

 dental finds, and for this reason they are among the rarest of known 

 Paleozoic animals; they are the " fancy fossils" of the local collectors 

 and the " choice specimens" of the museums. All of this is, however, 

 due to the accident of preservation plus their great destruction 

 through weathering. That starfishes and ophiurids were common, 

 though probably not so abundant as aulurids, is proven when they are 

 located in their entombing sediment and then quarried for. This 

 is best seen in the well-known Lower Devonic slates of Bundenbach, 

 where the quarrying for roofing material has produced as many 

 starfishes as all other localities put together. A great variety 

 has also been secured here, so that it is the only locality and time 

 of which we can say that we know the starfish fauna. The most 

 remarkable starfish find, however, is that made near Saugerties, 

 New York, where over 400 examples of the Middle Devonic 

 Devonaster eucharis were found in a fine-grained, somewhat muddy 

 sandstone, extending over an area of 200 square feet. They occur 

 as natural molds, and as the animals are found closely associated 

 with Grammy sia, it is thought that while feeding on these bivalves 



