Mr. W. King on some Families and Genera of Corals. 389 



bifurcating ; radiating from a small root ; running parallel to, and 

 at a short distance from each other, on one plane ; and giving off 

 bilaterally numerous, short, simple branches, of which opposite 

 pairs conjoin midway between the stems arcuately or at an 

 ascending angle. Branches occasionally modified into stems. Cel- 

 lules on the inner or upper surface of the fronds, on both stems 

 and branches, imbricated, and distributed in longitudinal series. 

 Series of cellules separated from each other by a dividing ridge. 

 (?) Gemmuliferous vesicles on the dividing ridges. 



Type, Retepora virgulacea, Phillips : a Permian species. 



Gen. Phyllopora'^, King. 



A Fenestellidia, consisting of infundibuliform, folded, perfo- 

 rated fronds or foliaceous expansions. Cellules on the whole of 

 the outer or under surface of the fronds, and planted more or 

 less approximating to a position at right angles to the plane of 

 the capillary-tubular basal plate. Cellule-apertures with plain 

 margins, and parallel to the surface of the fronds. 



Type, Gorgonia Ehrenbergi, Geinitz {=Fenestella permiana. 

 King, Catalogue, p. 6). 



Fam. Thamniscid^, King. 



It is proposed to include in this family certain shrub-like ge- 

 nera of palaeozoic ciliobrachiate corals possessing the bi-struc- 

 tural and polypidomial characters of Fenestellidce, but having free 

 stems and branches. It embraces the two following genera, and 

 apparently Mr. M'Coy^s Ichthyorachis. 



Gen. Thamniscusf, King. 



The typical Thamniscidia. Stems frequently and iiTegularly 

 bifurcating more or less on one plane : celluliferous on the side 

 overlooking the imaginary axis of the coral. Cellules imbricated, 

 and arranged in quincunx. Gemmuliferous vesicles overlying the 

 cellule-apertures. 



Type, Ceratophytes dubius, Schlotheim : a Permian species. 



Gen. AcanthocladiaXi King. 

 A Thamniscidia. Stems symmetrically and bilaterally branched 

 more or less on one plane, rarely bifurcating. Branches short, 

 simple, occasionally elongated and becoming bilaterally branched. 

 Stems and brariches celluliferous on the side overlooking the ima- 

 ginary axis of the coral. Cellules imbricated, and arranged in 



* Etym. ypvXKov, a leaf; nopos, a perforation, 

 t Etyni. dafxvia-Kos, a little shrub. 



J Etyin. aKau6a, a spine; K\a8oi, a branch : in reference to the spine- 

 like branches of the coral. 



