348 



MOLLUSCOIDEA-^ BEYOZOA 



PHYLUM V 



deiuoiistiated tlic luucli greater importance of zooocial characters, a decided advance 

 was made. Levinsen's studies upon the recent Cheilostoniata have resulted in a 

 splendid, detailed classification which unfortunately depends upon characters making 

 it difficult of application to the fossil forms. Only l)rief descrijitions of the more 

 imp(jrtant genera, or those having numerous fossil representatives, can be introduced 

 here. 



Suborder A. ANASCA Levinsen. 



Gompcnsation sac wanting; frontal ivall membraneous or calcareous, defressed and 

 surrounded by raised margins; ofercukor and subo'percular areas not sefarated by a 

 calcareous bar. 



Family 1. Aeteidae Hincks. 



Zoarium unilinear, adnate ; zocrcia partially erect, ivith membraneous apertures. 

 Aetea Lam. Tertiary and Recent ; Euroi^e. 



Family 2. Eucrateidae Hincks. 



Zoaria branching, erect and free, or recumbent. Zooecia uniserial or biserial, 

 ■pyriform, vnth a sub-terminal and usually oblique aperture. Avicularian and 



vibracular appendages wanting. Cre- 

 taceous to Recent. 



Eucratea Lamx. (Fig. 508). 

 Zoaria entirely decumbent, or com- 

 posed of a creeping adherent base 

 and erect branching shoots. Zooecia 

 calcareous or sub-calcareous, rising 

 one from another so as to form 

 single series. Branches springing 

 from the front of a zocecium below 

 Fio. 508. the aperture. Cretaceous to Recent. 



Kucratea lahiaUi (Novak). Cenonianian ; Velim. Boliemia. Gemellaria Savigny ; Notamia 



A, Zoariiiiii, l/j. B Zooecia, tliree of them with IVactured -r<i • mi- i -n j. 



walls, higiiiy magnified (after Novak). Fleming. Tertiary and Recent. 



Family 3. Scrupocellariidae Busk. 



Zoarium erect, 'usually jointed, dichotomously branching, phytoid,. Zooxia in two 

 or more series, closely united and arranged in the same plane. Sessile avicularia and 

 vibracula generally present. Tertiary and Recent. 



Menipea, Caberea Lamx. ; Hcrupocellaria Van Bened. Eocene and Recent. 



Family 4. Cellulariidae Levinsen. {tialicornariadac Busk). 



Zoarium erect, sub-cylindrical, dichotomously branching, usually jointed. Zoaxia 

 rhomboidal or hexagonal, each corresponding to an area, and, disposed in series about an 

 imaginary axis. Front depressed, usually concave. Orifice crescentic or semicircular, 

 situated slightly above the centre of the cell. Ooscia inconspicuous, opening at or near 

 the summit of the area above the orifice. Avicularia iisually j)resent. Cretaceous to 

 Recent. 



Cellularia Paihis {Cellaria Lam.; Salicornuria Cuv.) (Fig. 509). Zoarium jointed. 



