E. H. Barbour — Medusina Walcotti. 505 



Art. XLIV. — Medusina Walcotti, a Carboniferous Jellyfish; 

 by Erwin H. Barbour. 



The purpose of this paper is to announce briefly the occur- 

 rence of jelly fishes in the Carboniferous limestone of Nebraska, 

 and to propose a new species, Medusina walcotti. 



In exploring the quarries and exposures of the State, certain 

 quadripartite objects suggesting the form of jelly fishes have 

 long attracted the writer's attention. They are large and 

 coarse, and at first were assumed to be imitative concretions. 

 However, the total number observed seems to strengthen the 

 probability that they are of organic origin. In the fall of 1913, 

 while conducting a field class through the Burlington quarries, 

 located about two miles southwest of South Bend, they were 

 noted again in a new locality, and three specimens were 

 obtained. Two of these were unusual examples, and showed 

 sufficient structure to identify them with the Medusae. 



Dr. Charles D. Walcott, to whom a specimen was submitted, 

 concurs in the belief that these are jelly fishes. Since this 

 group is composed so largely of water, in some species as 

 much as 99 per cent, or more strictly speaking excessively 

 watery gelatine, the wonder is that even traces of such delicate 

 and perishable organisms are to be found. That they are 

 found at all is due to the toughness of their filmy skins. Some 

 of the larger and coarser varieties are even cartilaginous. 

 Under especially favorable conditions, the impressions of jelly 

 fishes are left in fine sands and mud. In this connection, it 

 may be of interest to note that the United States Geological 

 Survey has a collection of 9,000 specimens of jelly fishes. 

 They are reported from the Cambrian, Jurassic, Permian, and 

 Cretaceous. Their period of greatest abundance seems to have 

 been the Cretaceous. We recall no reports of fossil Medusae 

 from the Carboniferous, outside of Nebraska. Those found in 

 Nebraska are in upper Pennsylvania!! strata. According to 

 Mr. W. W. Stoner, mechanical engineer in charge of the 

 Burlington quarries, these casts occur in considerable numbers. 

 However, in a hurried visit but three were secured. The best 

 of these is shown in fig. 1 . They are of a good size, about 7 to 

 8 inches across (178 to 203 mm ). The convexity is 3 inches 

 (76 mm ). The oral lobes must have been large. They are 

 plainly indicated by the radiating angles of the mouth, aptly 

 called the mouth-cross. The mouth-cross is distinctly shown 

 in each of the three specimens from the Burlington quarry. 

 Traces of the more delicate structures are wanting. Yet it is 

 not impossible that some of them may be determined when a 

 larger number of specimens is at hand. The difference in the 

 geological horizon and the distance from regions productive 

 of fossil Medusae seem to justify the belief that these jelly 

 fishes are new. Arrangements have been made for the care- 



