or Little Known, Polyzoa. 137 



three imperfect fragments. The zoarium is small, branched, 

 bilaminate. The youngest zocecia and those at the margins 

 of the branches have one side produced into a long point, 

 with a small avicularium on the inner surface at the summit. 

 As age advances the summit disappears, and the mouth 

 becomes surrounded by a tumid peristome, with the avicu- 

 larium usually on the outer part of the ring. The pointed 

 process, with its surmounting avicularium, seems to be 

 formed before the operculum, as in the cells showing these 

 parts it cannot be detected. In a few older cells, where 

 the peristome is developed into a thick circular ring, 

 the internal mouth can be seen with a slit on its 

 superior side, that is, towards the upper end of the branches. 

 On the basal side of the mouth is a perforated plate, which 

 at first I thought was an ordinary zooecial opening similar 

 to that of Microporella renipuncta. It is, however, in 

 reality the opening of the ocecium. In young cells this 

 appears first as a cup-shaped elevation, which becomes 

 covered by a perforated plate, and gradually sinks into the 

 substance of the zooecium. The most curious circumstance 

 is that, although it would appear to be below the mouth, it 

 is really above it, owing to the peculiar reversal of the 

 mouth. It is evidently closely allied to Lekythopora 

 hystrix (M'G.), where the ooecia and oral avicularia are 

 similar. The shape of the operculum is similar in both, but 

 I have not yet made the necessary examination to ascertain 

 if the position of the ocecium in Lekythopora is also 

 superior, although seemingly inferior. The two species are 

 most remarkable, and I hope shortly to be able to give a 

 more detailed account of their structure. 



Family Hoknekid^e. 

 Ldmonea interjuncta, n. sp. 

 Zoarium dichotomously branched, branches spreading 

 irregularly, intricate, occasionally anastomosing ; numerous 

 bundles of prismatic, calcareous, radical tubes, passing from 

 the back of the branches, and attached either to the surface 

 on which it grows or to other branches. Zocecia usually 

 four in a series, of which the inner is shortest, turned much 

 forward, united side to side, separated by distinct grooves, 

 surface thickly covered with projecting pores. ' Posterior 

 surface finely grooved longitudinally, covered with elevated 

 perforations as in front ; surface marked by obscure, trans- 

 verse, concentric ridges. 



