24 ILLINOIS STATE GEOLOGICAL SURVEY CIRCULAR 326 



in a 2-mm distance, measured parallel to the length of the zoarium, is variable from 

 six entire zooecia and a portion of a seventh (one of 200 measurements) to nine 

 complete zooecia and a part of a tenth (41 of 200 measurements) . The base of the 

 mature zone is not defined crisply, but its position can be placed approximately 

 where diaphragm spacing diminishes most noticeably. 



The specific name alludes to the paucity of the acanthopores . 



Distribution. — Localities 2, 4, 6, 7, 8, 10. 



Types. — Illinois State Geological Survey, holotype 12P211; paratypes 12P7, 

 12P9, 12P69, 12P70, 12P74, 12P93, 12P96, 12P108, 12P133, 12P166, 12P168, 

 12P169, 12P178, 12P185, 12P202, 12P213, 12P217, 12P226, 12P228. 



Suborder INTEGRATA Ulrich & Bassler, 1904 



Family AMPLEXOPORIDAE Miller, 1889 



Genus MONOTRYPELLA Ulrich, 1882 



Type species: Monotrypella aequalis Ulrich 



MONOTRYPELLA NORMALIS Perry, n. sp. 



Plate 5, figures 1-3 



External features. — Zoarium ramose, solid, the larger of two fragments 

 21 mm long and 11 mm in maximum diameter. Surface smooth, exhibiting maculae 

 that are 4.0 to 5.0 mm apart, measuring from center to center, and composed of 

 zooecia above average in size and intercalated smaller cells. 



Tangential section. — Zooecia angular to somewhat subangular and generally 

 five- or six-sided; most commonly (14 of 20 measurements) nine entire zooecia 

 and part of tenth in 2 mm, measuring parallel to length of zoarium; less commonly 

 (four of 20 measurements) eight complete zooecia and part of ninth or more rarely 

 (two of 20 measurements) ten entire zooecia and portion of eleventh in this distance. 

 Zooecial walls thin (0.01 to 0.02 mm), composed of fine laminae paralleling mar- 

 gins of zooecial apertures, and generally appearing amalgamate but locally clearly 

 integrate. Angular to subround cells, smaller than average zooecia, and simulating 

 mesopores are common. Areas of zooecia above average in size and intercalated 

 smaller cells represent maculae. Acanthopores lacking. 



Longitudinal section. — Zooecia erect, thin-walled in axis, and bending 

 gradually toward zoarial surface, the curvature increasing somewhat at base of 

 mature zone where zooecial wall thickness increases and diaphragm spacing dimin- 

 ishes. Zooecial wall in mature zone composed of laminae acutely to moderately 

 convex outward and usually clearly integrate; wall laminae continuous into dia- 

 phragms; line of demarcation narrower and more sharply defined where zooecial 

 wall laminae are acutely convex outward, wider and somewhat vaguely defined 

 where wall laminae are more broadly convex outward. Diaphragms in axis usually 

 spaced from two to six zooecial diameters apart but lacking through a distance as 

 much as 4 mm in some zooecia; in mature zone diaphragms usually spaced from 

 somewhat less than one-half to l\ zooecial diameters apart; diaphragm spacing 

 gradually diminishes from center of axis to base of mature zone. Mesopores and 

 acanthopores absent. 



Remarks. — Monotrypella normalis is represented in the Spechts Ferry col- 

 lections by two specimens, each from a different locality, from which three tangen- 

 tial and two longitudinal sections, as well as one transverse section, were pre- 

 pared. The paratype is a fragment from near the distal extremity of the zoarium, 



