BRYOZOA. 105 
Classification.} 
According to Nitsche the Holobranchia are again divisible into two very unequal 
groups, the Ectoprocta, in which the lophophore surrounds the mouth only, and the 
Entoprocta, in which it encloses both the orifices of the alimentary canal. 
The former division embraces the great majority of the Bryozoa, and the second 
of the two orders, Phylactolemata and Gymnolemata, of Allman, into which it is 
almost universally divided, comprises, with very few exceptions, all the living and 
fossil marine forms. In the Phylactolwmata the lophophere is open on one side and 
horseshoe-shaped ; in the Gymnolwmata it is complete and circular. 
The second of these orders has been divided into five suborders, the Chilostomata, 
Cryptostomata, Trepostomata, Cyclostomata, and Ctenostomata, all of which seem to be 
represented in the paleozoic rocks of America. 
SYSTEMATIC CLASSIFICATION OF PALEOZOIUC BRYOZOA.* 
Sub-kingdom WoO ath SG Ou BA 
Class BRYOZOA, Ehrenberg. 
Sub-class HOLOBRANCHIA, Ray Lankester. 
Order GYMNOLAUMATA, Allman. 
Sub-order CHILOSTOMATA, Busk. 
Orifice of zocecium situated laterally, of smaller diameter than the zocecium, 
closed by a movable cover (operculum). Ova usually matured in external marsupia. 
Appendicular organs (avicularia and vibracula) frequently present. 
Family PALESCHARID#, Ulrich. 
Genus: Paleschara HALL. 
Family  WoORTHENOPORID®, Ulrich. (Provisional) 
Genus: Worthenopora ULRICH. 
Family PHACELOPORID®, Ulrich. 
Genus: Phacelopora ULRICH. 
Suborder CRYPTOSTOMATA, Vine. 
Primitive zocecium as in the Chilostomata. Orifice concealed, at the bottom of a 
tubular shaft or vestibule, which may become intersected by straight diaphragms or 
hemisepta through the direct super-imposition of successively developed layers of 
polypides. External orifice rounded, often closed by a perforated or entire cover. 
_ External marsupia and avicularia wanting. 
* The classification here published is a slight improvement upon the scheme in vol. viii, Il. Geol. Sur. Rep'ts. That one 
represented the state of our knowledge on the subject in 1887-89. 
