112 PROCEEDINGS OF THE NATIONAL MUSEUM. vol.01. 



The ovicell is of the exact type of the Tretocycloeciidae ; the tuT3es 

 which perforate it are often closed by a calcareous lamella. The 

 zoaria of Psilosolen differ from Alveolaria only in a more elongated 

 form of the branches and in the absence of dorsal budding. Alveo- 

 laria is an aggregation of non-digitate colonies like Telepoi^a Canu 

 and Bassler 1920. When we know the internal structure of this lat- 

 ter genus from thin sections it may perhaps be necessary to unite it 

 with Alveolariu. 



Occurre7ice. — Pliocene (Plaisancian) : Sudbourne Church, etc., Suf- 

 folk, England. 



Plesiotijpes.— Cat. No. 60363 U.S.N.M. 



PSILOSOLEN, new genus. 



P^Zos-unfurnished and solen, tube. 



Tretocycloeciidae in which there are no adventitious tubes. The 

 tubes are cylindrical, with peripheral gemmation. 



Genotype. — Psilosolen capitiferax^ new species. 



Range. — Pleistocene, Eecent. 



The ovicell is a swelling perforated by the tubes as in the Dia- 

 peroeciidae, but it is not inserted in the tubes themselves. On the 

 contrary, the ovicell is perpendicular to the tubes and surrounds 

 only the peristomes, as in the family Tretocycloeciidae, where this 

 new genus may be naturally classed. The ovicell is little convex 

 and very different from the elongated and very salient sac of the 

 Ascosoeciidae. 



It is remarkable to note again that through the geological ages 

 it is the simplest form of the family that has persisted. The Cre- 

 taceous and Tertiary genera of this family are more complicated and 

 provided with adventitious tubes. 



PSILOSOLEN CAPITIFERAX, new species. 



Plate 13, fig. 8. 

 Description.— T\iQ zoarium is free, with the form of Entalophora^ 

 more or less compressed, dichotomous ; the extremity of the branches 

 is enlarged, flattened, and hears the ovicell. The tubes are visible, 

 seiiiirated by a furrow, convex, wrinkled transversely, somewhat 

 widened at the summit; the peristome is thin, salient, elliptical or 

 suborbicular. The ovicell is a swelling covering the extremity of 

 a branch; it is perforated by a dozen tubes, some of which are 

 closed by a finely porous diaphragm. 



Diameter of peristome 0. 16-0. 18 mm. 



Distance between peristomes __ . 50-1. 35 mm. 



Measurements. — ^Diameter of orifice .12 mm. 



Separation of peristomes Variable. 



Diameter of tube . 18- . 20 mm. 



