NORTH AMERICAN EARLY TERTIARY BRYOZOA. 785 



IDMIDRONEA MAXILLARIS Lonsdale, 1845. 



Plate 131, figs. 1-7. 

 1S45. Idmonca maxUlaris 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 iniu-iUaris 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. 



-Diameter of the tubes 0.16-0.20 mm. 



Mea >nts - I Distance between the fascicles. 0.30-0.40 mm. 



{ Width of the fascicles 0.17 mm. 



Width of the branches 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 Idmonca magnir ever set-, but differs from it in its totally different longi- 

 tudinal section, owing to the presence of innumerable firmatopores. 



It differs from Idmidronca rosa'cea and Idmidronca culler, 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). 



Plesiotypes.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 are 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. 

 5539920 Bull. 106 50 



