428 PALAEONTOLOGY OF ILLINOIS. 



The species is identified with authentic examples of the spe- 

 cies, agreeing in most respects with Rominger's brief descrip- 

 tion. The interspaces are, however, not vesiculose, but occu- 

 pied by unmistakable mesopores, with open apertures. The 

 structure, therefore, is not as in Fistulipora. Should an exam- 

 ination of Rominger's original types prove his species distinct, 

 then Nicholson's name will stand. 



Position and locality: Common at Buffalo and Davenport in 

 Iowa, Andalusia and Rock Island, in 111., and at several locali- 

 ties in Northern Michigan and Western Ontario. 



LEIOCLEMA WACHSMUTHI Ulrich. 



PL LXXV, flg. 7. 7b.. 



Zoarium a thin expansion, consisting of one or more super- 

 imposed layers, each one mm. or less in thickness; the lower 

 surface provided with a finely wrinkled epithecal membrane. 

 Surface irregularly undulating or montiferous, occasionally 

 showing a tendency to throw up short, slender branches, from 

 one to two mm. in diameter. Zocecia about six in the space of 

 two mm. with thin walls, at first prostrate, then curving and 

 opening perpendicularly to the surface. Apertures mostly oval, 

 some circular, their longer diameter about 0.2 mm.; their mar- 

 gins beset with small spinules, the surface projections of the 

 acanthopores which occasionally project into the visceral cavity 

 and give the aperture a floriform aspect. Mesopores angular, 

 very numerous, completely encircling the zocecia in from one to 

 three rows. 



The thin laminar growth, and the exceeding abundance of the 

 mesopores are the most marked features of this species. 



Position and locality: Kinderhook group, Marshalltown, la. 



LEIOCLEMA SUBGLOBOSUM Ulrich. 



PL LXXV, fig. 8, 8b. 



Zoarium subglobose, pedunculate, base sometimes expanded. 

 Surface smooth. Zooecia radiating out in curved lines in all 

 directions from the center of the base. Tube walls thicken in- 



