64 A MONOGRAPH OF THE TERTIARY POLYZOA OP VICTORIA. 



Family Micpopopellid^;. 



Zoarium encrusting or erect and uni- or bilaminate. Zooecia horizontal, 

 calcareous and destitute of membraneous area; front with a single pore or 

 perforated plate or with several pores opening into the perivisceral cavity; 

 thyrostome arched above, entire below. Ooecia prominent and external, or modified 

 zooecia. 



The essential character of this family is the presence of one or more pores 

 opening directly into the cavity of the zooeciurn. Two groups, differing in several 

 points, but agreeing in the cardinal one of the zooecial pore, are included. In the 

 one, containing of those here described, Microporella and Tessaradonia, the ocecia 

 are of the usual marsupial form, and external. The other, of which Adeona 

 (including Adeonellopsis) is the only genus, differs chiefly in the ooecia not being 

 external and distinct, but being internal and consisting of modified zooecia {goncecia 

 of Hincks.) It also differs in having, in addition to ordinary sessile avicularia, other 

 larger avicularia developed in special cells variously distributed among the zooecia. 

 These characters, however, although important and very interesting, can scarcely be 

 considered of sufficient value to distinguish a separate family. The genus Adeonella 

 of Busk agrees with Adeona in having goncecia and vicarious avicularia, but differs 

 in having the pore on the anterior surface, when present, formed by a process from 

 each side of the lower lips uniting to form an arch beneath, which it opens into the 

 peristomial chamber in front of the true thyrostome. In the only species which I 

 have found fossil there is no pore, but other specimens may probably show it. I 

 have referred Adeonella to the Schizoporellidse, to which this species seems to 

 belong, as do also A. (Eschara) dispar (McG.) and A. platalea (Busk), as well as 

 several others, at least of the Challenger species.* 



Microporella, Gray. 



Thyrostome arched above, straight below ; a single circular or lunate pore 

 {try pa of Gregory), or a perforated plate below the lower lip. Ocecia external. 



1. M. ciliata, Linn, sp. PL IX., fig. 3. 



Leprcdia ciliata, Busk, B.M.C., Pt. II., 73; id., Crag Pol., 42; McG., P.Z.V., 

 37 ; Microporella ciliata, Hincks, B.M.P., 206 ; Busk, C.P., Pt. L, 138 ; Waters, 

 Q.J.G.S., 1882, p. 266 and 508; id., 1887, p. 53; McG., P.Z.V., 175. For other 

 references and synonyms, see B.M.P. and Miss Jelly's Catalogue. 



Zoarium encrusting. Zooecia distinct, ovate, granular, several (usually four) 

 oral spines ; a small lunate or rounded pore {trypa) below the thyrostome ; a sessile 



*For a discussion of this subject see Hincks, A.M.N.H., Feb., 1887. 



