48 



THE DEVONIAN OF MISSOURI. 



COELENTERATA 



Class ANTHOZOA 



Subclass Tetracoralla 



Family Zaphrentidae 



Genus Streptelasma Hall 



Streplelasma cooperensis n. sp. 

 Plate. 1, figures 6- and 7 



Corallum simple, conical, slightly curved, pointed at the base Epitheca com- 

 plete, showing longitudinal septal furrows. Largest specimen collected 8 cm. long, 

 34 mm. wide at the top: average size about 6 cm. long. Calyx with steep walls, depth 

 about half the height of the corallum. Septae rather poorly developed in the calyx 

 but well developed near the base of the corallite. 25 septae that reach nearly to the 

 middle one centimeter from the base of an ordinary specimen; 33 septae 2 centimeters 

 from the base with some indications of secondary septae; 41 primary septae 45 mm. 

 from the base with a like number of short secondary septae. Dissepiments few and 

 present only near the margin. Subcentral fossula 8 mm. wide and 10 mm. deep in 

 specimens of ordinary size. 



The calyx is completely filled with solid rock in all of our specimens and for that 

 reason no figures of that part can be made. The species resembles Streplelasma prolifica 

 Billings but the number of septae is much smaller and the secondary septae are not 

 so well developed. 



Occurrence — Abundant in the Callaway of Moniteau and Boone Counties; present 

 in the Cooper of the same counties. 



1 ^^2 



Fig. 1. Sections of Streptelasma cooperensis Branson. 



1. A vertical section which retains only 1/3 of the cup. The basal part of the 

 specimen is missing. (X3/2). 



2. A cross section about two centimeters from the base. (X3/2) 



3. A cross section about 6 centimeters from the base. (X3/2) 



