DIASTOPOEA. 133 



SYNOPSIS OF SPECIES. 



I. Zocecia cylindrical. 



A. Zoarium bilaminate. 



a. Zocecia visible throughout. 



Zoarium frondose. 



peristomes well raised ; peristomes irregular foliacea. 



peristomes slightly raised; peristomes sub- 



regular davidsoni. 



Zoarium ribbon-shaped. 



peristomes raised ; peristomes irregular ... calloviensis. 



b. Zooecia visible at ends michelini. 



B. Zoarium unilaminate lamourouxi. 



C. Zoarium reticular retiformis. 



II. Zocecia lozenge-shaped lamettosa. 



Family IDMONIIDJE. 



SYNONYMY : 



Tubigerldce, pars, D'Orbigny. 

 Tubuliporidce, pars, Johnston ; Smitt ; and Hincks. 

 Idmoniidte, pars, Busk ; MacGillivray ; Pergens and Meunier ; Marsson. 



Diagnosis Cyclostomata Tubulata in which the zocecia are simple, 

 open tubes, and grow into adnate or erect branching zoaria. The 

 zoarium is branched, and the zooecia open only on one side of it. 

 The apertures are disposed in regular transverse series, usually 

 alternately arranged. 



Affinities. This family was founded by Busk in 1859 for a group 

 including Hornera, Terebellaria, Idmonea, Pustulopora, Cricopora, 

 and Cyrtopora. Smitt removed Hornera from this group as 

 a separate family, and though this course has not been adopted 

 by MacGillivray or Pergens, it seems to me wisest to accept it. 

 Pergens, in 1886, raised Pustulopora and its allies into the family 

 Entalophoridae, and also pointed out that Cyrtopora belonged to 

 another distinct type. Moreover, Terebellaria is more different 

 from Idmonea than is any of the others. 



The Idmoniidae are therefore left as a small group, embracing 

 those Tubulata in which the zooecia open on one side only of the 



