ALLMAN, ON POLYZOA. 37 
structure ; and as the fresh-water species afford fine typical 
examples of the class, a work devoted to the anatomy of 
these will apply in all essential points to that of the entire 
class, while such points of structure as are peculiar to the 
fresh-water forms will only tend to illustrate and explain the 
structure of the marine ones; so that the present Mono- 
graph, in its anatomical relations, may be fairly regarded as 
a general treatise on polyzoal organization.” 
After a full discussion of the anatomy, physiology, and 
homologies of the Polyzoa in general, the author proceeds 
to the zoographical part of his subject, including the history 
and biblography of the Fresh-water Polyzoa—their habits, 
geographical range, and classification. To which succeed 
the diagnoses, synonymy, and natural history of the genera 
and species; thus completely exhausting the subject, and 
bringing our knowledge of it, in most essential particulars, 
up to the present moment. 
The classification of the Polyzoa adopted by Professor 
Allman will be apparent in the following tabular view of their 
orders and sub-orders : 
Orders. Sub-orders. 
Lophophore bilateral ; (Arms of lophophore free or 
mouth with an epistome. | obsolete. j Lornorea. 
PHYLACTOLASMATA | Arms of lophophore united at } Prices mien 
the extremities. ; 
Polypide only partially re-] UrnaTeLira 
tractile P (fresh-water). 
PALUDICELLEA 
tile ; evagination of tenta- (fresh-water). 
Polypide completely vente} 
cular sheath imperfect. 
Polypide completely retrac- 
tile ; evagination perfect ; | CycLostoMaTA 
orifice of cell destitute of { (marine). 
GYMNOLAMATA. . moveable appendage. 
Polypide completely retrac- 
tile; evagination perfect ; | 
a circle of sete attached to Crenostomata 
the invertible portion, and { (marine).4 
acting as an operculum in | 
the retracted state. 2 
tile; evagination perfect ; 
orifice of the cell with a 
moveable lip. 
CHEILOSTOMATA 
(marine). 
Polypide completely at 
