138 Prof. Bailey on some new Fossil Infusoria. 



self-division." He appears to have seen no fossil species, as he 

 describes none but the P. Germanicus, which he found alive in 

 sea water at Cuxhaven. Our species may be thus characterized : 

 Podiscus Rogersi, (figs. 1 and 2.) Lorica large, orbicular 

 and compressed, having three to seven hyaline lateral processes 

 placed on an elevated circle, within which the disc is slightly 

 concave, and outside of which the surface is part of the frustum 

 of a cone. The whole surface is beautifully punctate, in a man- 

 ner to which no engraving could do justice. The most compli- 

 cated markings on the Coscinodisci scarcely rival the elaborate 

 ornaments of this truly elegant creature. This species is quite 

 common in the fossil state at Petersburg, Va. and also occurs at 

 Piscataway, Md. Our figure is intended merely to show the 

 general size, and the position of the feet. Fig. 1 shows a view 

 of the disc, and fig. 2 is half of an individual seen edgewise. 



2. Zygoceros Tuomeyi, nob. (figs. 3 to 9.) The remarkable 

 form represented in outline by these figures, occurs both at Pe- 

 tersburg and at Piscataway. I am disposed to refer it to Ehren- 

 berg's genus Zygoceros, which he describes as being "free, Na- 

 vicula shaped, compressed and bivalved, each end provided with 

 two perforated horns." The figures above referred to will give 

 a better idea of the shape of our species than words will furnish, 

 but the following is offered as an attempt to characterize it. 



Zygoceros Tuomeyi. Lorica having at each end two obtuse 

 horns, with swollen bases, between which are one to three globu- 

 lar projections on each side ; those in the middle being largest, 

 and often bearing two spines. At the base of each of the swell- 

 ings the shell often shows perforations, (see a, a, a, figs. 3 and 4,) 

 and the whole surface of the shell is covered with shagreen-like 

 asperities. I dedicate this species to M. Tuomey, Esq., to whom 

 I am indebted for fine specimens of infusorial and other fossils 

 from the neighborhood of Petersburg. Fig. 3 shows a large and 

 perfect individual ; fig. 4, a smaller one ; fig. 5, a young individ- 

 ual ; fig. 6, one seen obliquely; fig. 7, an oblique view of one 

 half; fig. 8, a top view; and fig. 9 shows two halves of different 

 individuals united in the manner in which the.y probably formed 

 chains when living. 



3. Zygoceros rhombus 1 (figs. 10 and 11.) Our figure repre- 

 sents a species which so closely resembles the Z. rhombus of 

 Ehrenberg, that I am inclined to consider it as most closely allied 



