SYSTEMATIC DESCRIPTIONS. 
Order CHEILOSTOMATA Busk. 
Suborder ANASCA Levinsen. 
A zooecial hydrostatic system is absent, but a zoarial hydrostatic system is 
present, and is included between the cryptocyst and the ectocyst. 
The Anasca are classified under the three divisions Malacostega, Coilostega, 
and Pseudostega. 
Division I. MALACOSTEGA Levinsen, 1909. 
The parietal muscles are attached to the cryptocyst, which is always chitinous. 
The operculum is a membranous valve (fig. 16). In the 
fossil forms the frontal Avail is quite or partially uncalicified. 
The families of this division are as follows, those in the 
first column being represented in this Avork : 
Electrinidae D'Orbigny, 1351. Bicellariidae Smitt, 1867. 
Membraniporae Canu and Flustridae Smitt, 1867. 
Bassler, 1917. Notamiidae Hincks, 1880. 
Aeteidae Smitt, 1867. 
Scrupocellariidae Levinsen, 
1909. 
Farciminariidae Busk, 1884. 
Eucratiidae Hincks, 1880. 
Family ELECTRINIDAE D’Orbigny, 1851. 
Bibliography ( Anatomical ). — 1865, Smitt, Om Hafs-Bryozoernas 
utveckling och fettkroppar, Oiwersigt Kongl. Vetenskaps-Akade- 
miens Forhandlingar, vol. 22, pi. 1, figs. 1-10; pi. 2, figs. 1-A.- — 1868, Schneider, Ueber die 
EntAvickelung von Cyphonautes compressus zu Membranipora pilosa, Sitzungsberichte der 
)Gesellschaft der naturforschenden Freunde, pi. 16. — 1871, Nitsche. Beitrage zur Kennt- 
nis der Bryozoen. III. Ueber die Anatomie und Entwickelungsgeschichte von Flustra 
membranacea, Zeitschrift fiir wissenschaftliche Zoologie, vol. 21, pis. 4-6. — 1875, Repiachoff, 
Zur Entwickelungsgeschichte der Tendra zostericola, Zeitschrift fiir wissenschaftliche Zoolo- 
gie, vol. 25, pis. 7-9. — 1877, Barrois, Recherehes sur l’embryologie des Bryozoaires, Travaus 
de Institut de Zoologie, Lille, fasc. 1, pi. 4. — 1880, Repiachoff, On the Morphology of the 
Bryozoa (in Russian), Memoires Soeietg Nouvelle Russe., vol. 6, pis. 1, 2. — 1900, Calvkt, Con- 
tribution a l’histoire naturelle des Bryozoaires ectoproctes marins, Travaux Institut Zoologie 
de Universite de Montpellier, Mem. 8, pi. 6, figs. 7-10. — 1907, Bogolepow, Wachstum und Leben 
der Kolonien der Tendra zostericola an den Glasern der Aquarien, Zeit. Anzeige, vol. 32, pp. 
306-316. — 1908, Robertson,. The incrusting Cheilostomatous Bryozoa of the AVest Coast of 
North America, University of California Publications, vol. 4, No. 5, p. 269, pi. 17, figs. 24, 25. 
fm 
- cryp 
""pm 
Fig. 16. — Sketch illustrat- 
ing structure of the 
Malacostega. 
Transverse section of a 
zooecium of a Flustrine 
form, showing the mem- 
branous ectocyst (/to, fron- 
tal membrane), the mem- 
branous cryptocyst {cryp), 
and the parietal muscles 
(p. m.). (After Harmer, 
1902.) 
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