DIASTOPOEA. 
127 
Affinities. 
This genus is hy no means the most typical or central member of 
the family to which it gives its name. In the Catalogue of the 
Jurassic Bryozoa, as a concession to the neontologists, the name 
Tubuliporiclse was accepted instead of Diastoporidse, which has 
been adopted by the majority of palseontologists. After a study of 
the genus Tuhidipora it appears necessary to include that genus in 
the Idmoniidae. It seems therefore advisable to abandon the name 
Tubuliporidae, unless the whole of the Diastoporidan and Idmonian 
series are included in one family, an arrangement which few 
palaeontologists would be likely to adopt. 
Diastopora is accepted for Diastoporidae which are fi’ondose and 
erect, while the allied encrusting forms are referred to Berenicea. 
This course does not agree with the definitions of most zoologists ; 
and it is even less in accord with their practice. If any generic 
separation be made between the adnate and foliaceous species, then 
certainly the name Diastopora must be retained for the latter, for it 
was founded for a single erect species from the Bathonian. Heon- 
tologists have gradually adopted Diastopora for both the adnate 
and foliaceous species ; and then, though covering both types by 
their diagnosis of the genus, they have removed the erect species to 
Mesenteripora and left in Diastopora the adnate forms alone. Thus 
Busk, in the Catalogue of Cyclostomata in the British Museum, 
includes in Diastopora four species, all of which are adnate, while 
the one erect species is assigned to Mesenteripora ; Hincks accepts 
four British species of Diastopora^ all of which are adnate, though 
he includes Mesenteripora as a synonym for the “foliaceous bi- 
laminate forms.” 
The most difficult question in regard to this genus is its relation 
to Mesenteripora, which was founded by de Blainville ^ for bilaminar 
species, Diastopora being restricted to unilaminar species in which 
the zooecia occur only on one face of the frond. D’Orbigny^ 
accepted both genera, practically in de Blainville’ s sense ; but he 
introduced the idea of a lame germinate, which in Mesenteripora 
forms a median layer, and in Diastopora covers the reverse face. 
Pergens accepted both genera, mainly on the basis of this ‘ germinal 
* De Blainville : Man. Act. 1834, p. 432. 
* D’Orbigny: Bry. Cret. pp. 807, 825. 
