NORTH AMERICAN EARLY TERTIARY BRYOZOA. 
785 
IDMIDRONEA MAXILLARIS Lonsdale, 1845. 
Plate 131, figs. 1-7. 
1845. Idmonea maxillaris Lonsdale, Account of 26 species of Polyparia obtained from 
the Eocene-Tertiary formation of North America, Quarterly Journal Geological 
Society, London, vol. 1, p. 523, fig. 
1S62. Idmonea maxillaris Gabb and Horn, Monograph fossil Polyzoa of the Secondary 
and Tertiary formations of North America, Journal Academy Natural Sciences, 
Philadelphia, ser. 2, vol. 5, p. 167. 
Description. — The zoarium is formed of triangular, linear, irregular branches 
more or less distorted and cervicorn. The fascicles are very salient, quite close 
together, arranged alternately on each side of the median crest; they are formed 
of three zooecia. The tubes are invisible; the peristomes are thin and round. 
The dorsal is striated by numerous parallel firmatopores. 
Measurements — 
-Diameter of the tubes 
Distance between the fascicles 
Width of the fascicles 
Width of the branches 
0.16-0.20 mm. 
0.30-0.40 mm. 
0.17 mm. 
1.00 mm. 
Affinities. — The species is remarkable for the extraordinary development of 
the dorsal formed of a great number of firmatopores. They form a very thick 
collar on which the fascicles appear to incrust. In this respect the species much 
resembles Idmonea magnireversa. , but differs from it in its totally different longi- 
tudinal section, owing to the presence of innumerable firmatopores. 
It differs from Idmidronea rosa'cea and I drnidronea cutter , which have an 
identical transverse section, in the great saliency of the fascicles. 
Occurrence— Middle Jacksonian: Wilmington, North Carolina (very com- 
mon) ; near Lenuds Ferry, South Carolina (very common) ; Wantoot, South Caro- 
lina (type locality). 
Piesiotypes. — Cat. No. 65360, U.S.N.M. 
IDMIDRONEA CULTER, new species. 
Plate 132. figs. 1-10. 
Description, — The zoarium is formed of long, linear branches bifurcated with 
triangular transverse section. The fascicles arc little distinct, not salient, quite 
close together, and formed of three, four, or five zooecia; they are alternated on 
each side of the median crest, but they are adjacent to each other with the least 
abrasion. The tubes are invisible; the peristome is small, thin, round. The 
dorsal is semicylindrical, very thick, striated longitudinally by its large firm-* 
atopores. 
The transverse section is triangular; it has the form of a very thick knife , 
round at the back. This is always higher than wide, but the relation of the two 
dimensions is not constant. 
Affinities. — We have hesitated much to separate this species from Idmonea 
maxillaris Lonsdale, 1845, of which it appears to be a condition of weathering. 
55899— 20— Bull. 106 50 
