614 



BULLETIN 106, UNITED STATES NATIONAL MUSEUM. 



CLITHRIDIATE GROUP. 



The orifice is oval. The frontal is a very thick olocyst perforated by some 

 scattered avicularia. The ovicell is hyperstomial and lodged in the thickening of 

 the olocyst. 



It would be convenient, perhaps, to make a special family for this group; but 

 we are ignorant of the larva, and it is necessary to search first and find the analogous 

 or closely related recent species. 



Some species have very little of cumulate zooecia. 



Genus ACANTHIONELLA Canu and Bassler, 1917. 



1917. Acanthionella CANTT and BASSLER, Synopsis of American Early Tertiary Clieilostome 

 Bryozoa, Bulletin 96, United Slates National Museum, p. 72. 



The apertura is oval and bears a long lyrula. The frontal is a very thick 

 olocyst, in which are lodged some avicularia. The ovicell is hyperstomial: it is 



lodged in the thickening of the 



(> ~~\Z5r~v frontal of the distal zooecia ; it 



opens into the peristomie. 



G enotyp e. Acaiithionella 

 (Eschanfora) typicaGabb and 

 Horn, 1862. 



Range. M aastrichtia n 

 Jacksonian. 



This genus differs from Klei- 

 dionella in the presence of a 

 \'\ jHfiaS- lyrula and the rarity of cumu- 

 late zooecia. 



B '50 



ACANTHIONELLA OECIOPOROSA, new 

 species. 



Plate 17, figs. '1-14. 



FIG. 183. Cellepora ramulosa Busk, 1854. 

 A. Zoarium, natural size. B. Zooecium, X 50. C. Portion 

 of zoarium, X 25. (A-C after Busk, 1854.) 



Description. The zoarium 

 is free, bilamellar, with fronds 

 more or less rounded. The 

 oriented zooecia are indistinct; the frontal is a very thick olocyst perforated 

 by two to five small avicularia. The apertura (interior) is oval and garnished 

 by a long proximal lyrula; the peristomice (exterior) is orbicular; the peristomie 

 is very deep and contains sometimes an avicularium bearing the lyrula. The 

 ovicell is buried in the distal zooecia; it opens into the peristomie; it bears a 

 frontal area closed by a much branched spine. The young zooecia and the cumulate 

 zooecia are distinct, elongated, gibbose. The interzooecial avicularia are rare, of 

 the size of the zooecia, elliptical, and provided with a pivot. 



Measurements. Apertura iha=O.W mm. Zooecia fis 0.35 mm. 



(interior) U=0.14 mm. (interior) |fe=0.26 mm. 



