568 BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 



ADEONELLOPSIS GRANDIS, new species. 



Plate 99, figs. 11-18. 



Description. The zoarium is free, bilamellar, dichotomously branched, often 

 attaining more than 2 centimeters in length; the two lamellae are placed back 

 to back and are separated with difficulty. The ordinary zooecia are elongated, 

 distinct, lozenge-shaped, and separated by a furrow. The peristome is almost 

 complete and bears a large distal pore; the peristomie, which is rather deep, con- 

 tains a small, straight avicularium, triangular on the old zooecia and round on the 

 young, and a well-hidden aperture ; the peristomice is in the form of a crescent on 

 the young zooecia and rather regularly elliptical on the old ones. The ascopore is 

 stellate, very small, and close to the peristomial avicularia. On the line of the 

 areolae there are one or two round, simple, and little salient avicularia. The 

 gonoecia are larger than the ordinary zooecia; their ascopore is replaced by a 

 deep cribriform area perforated by four to six pores. 



. f 2=0.44 mm. . |Zs(7=0.44-0.50 mm. 



Measurements. Zooecia -L nonnm Gonoeciaj, ' 



[lz= 0.20-0.22 mm. (lsg=Q.30mm. 



External aperture f Zooecia =0.06 mm. 

 (width) lGonoecia=0.10mm. 



Variations. The peristomial avicularium is round when it is prominent (figs. 

 12, 15), but on the old zooecia with very thick walls it becomes triangular and 

 pointed; this transformation is quite remarkable, but it still does not permit one 

 to discover the function of the organ itself. The ascopore is visible only on the 

 young zooecia (fig. 14). On the others it is placed in the peristomice below the 

 avicularium but always quite visible. 



In thin transverse sections (fig. 16) the zooecia are very thick. The pleu- 

 rocystal elements, piled one on the other are grouped in transversal filaments. 



In tangential section, the ascopore is rarely distinct from the avicularium 

 (figs. 17, 18) because they are very close to one another. 



Affinities. This species differs from Adconellopsis transversa in its peristomial 

 avicularium, which is straight and not oblique, and in the size of the zoarium. 

 The zoarial dimensions permit the species to be classified among the good-sized 

 fossils useful in field determination. 



In its distal pore it resembles Adeonellopsis cy clops, but differs from it in the 

 absence of the cribriform area on the ordinary zooecia. 



Occurrence. Vicksburgian ("Chimney rock" of Marianna limestone): One 

 mile north of Monroeville, Alabama (very abundant). 



Cotypes.Cat. No. 64319, U.S.N.M. 



ADEONELLOPSIS GALEATA, new species. 

 Plate 99, figs. 1-10. 



Description. The zoarium is free, bilamellar, erect, formed of short, dichoto- 

 mously divided fronds; the two lamellae, placed back to back, are inseparable. 



