EETEXOA. 
29 
Diagnosis. 
Zoarium a flat frond, all in one plane. Long oval interspaces 
between the anastomosing branches. Branches laterally com- 
pressed, with long grooves along the sides. Obverse surface 
sharply ridged. 
Apertures all on the narrow obverse edges of the branches ; they 
are crowded and irregular in arrangement. The apertures are 
slightly raised ; there are from two to four series of apertures 
on the front of each stem. 
Dimensions. 
AVidth of the obverse edge of the branches ... 1’5 mm. 
Thickness of the branches (obverse to reverse) ... 2 ,, 
Distribution. 
Ilauterivian — Calcaire janne : Meil, near Neufchatel. 
Neocomian: Sainte-Croi.x, Yaud, Switzerland. 
Affinities. 
The Museum specimens of this species agree in all essentials 
with the characters shown in d’Orbign)-’s figures. But one 
specimen (D. 3666) has part of the obverse surface exceptionally 
well preserved, and there the peristomes project with slightly 
raised rims, as in ordinary Tubulate Cyclostomata. The number of 
apertures in the width of the stem in this specimen is three or four. 
LIST OF SPECIMENS. 
D. 3665. Three fragments of a zoarium and two others (on slide). Hauterivian— 
Calcaire jaune. Meil, near Neufchatel. Bruckmann Coll. 
D. 8666. A broken zoarium and fragment of the same mounted on a slide. 
Part of the front edge of the zoarium is well preserved. Haute- 
rivian — Calcaire jaune. Meil, near Nenfchatel. Bruckmann Coll. 
D. 3667. A zoarium showing reverse surface. Hauterivian — Calcaire jaune. 
Meil, near Neufchatel. Bnickmanu Coll. 
DOUBTFUL SPECIES. 
Retelea^ megalostomata^ Hennig, 1894 (Bry. Sver. Krit. ii., Cycl. : Lunds 
Univ. Arsskrift, vol. xxx., Acta Physiogr. No. viii. p. 39, pi. ii. tigs. 41, 42, 
and fig. 24, p. 40), from Campanian of Balsberg and Karlshamn, may be 
a species of Rctenoa. 
