84 On the Polyzoa of Mauritius. 



drical, surface marked by ridges and punctures, botli on the 

 front and dorsally, Zooecia in series one to three on alternate 

 sides of front of branches, in subparallel oblique series ; 

 zooecia increasing in height from within outwards, innermost 

 almost level with surface, outermost long, slender, exserted, 

 and projecting out on a plane with the general surface of the 

 zoarium ; outer zooecia with long vertical s])ines, inner with 

 short spines, bent in at right angles to orifice ; intermediate 

 zooecia with vertical and horizontal spines. Ooecia? 



It was at first a matter of doubt whether H. spinigera was 

 not a form of H. pectinata, Busk ; but an examination of the 

 type specimen of the latter showed several important differ- 

 ences. The zooecia of H. pectinata are larger and of stouter 

 build and are not so regularly arranged as in H. spinigera. 

 The zooecia in H. spinigera are arranged almost as regularly 

 as those in the genus Idmonea ; but the presence of the inter- 

 zocecial strijB and punctures indicates that the specimen 

 belongs to the former rather than to the latter genus. 



EXPLANATION OF THE PLATES. 



Plate VII. 



Fiff. 1. Di'pIcKcium simpk.r, nov. gen. et s-}^. la. Magnified, lb. Show- 

 ing suppression of internoile and ooecium. 

 Fi(/. 2. Mcmbranipora marfiinalis, n. sp. 

 Fig. 3. Memhrmiipora mauritiana, n. sp. Cells from edge of colony, well 



separated. 

 Fig. 4. Schizoporella ampla, n. sp. 4 a. Magnified cell, showing two 



avicularia. 4 b. Pyriform mandible of large avicularian cell 



(see fig. 4). 

 Fig. 5. Gigantopora lyncoides, Ridley. 5 a. Cell in which the avicularia 



have not joined to form the bridge and pore. 5 b. Primary orifice. 

 Fig. 6. Ketepora tenuis, n. sp. 6 a. Trabecula, magnified. G b. Fertile 



zooecium, enlarged. 6 c. Operculum. 6 d. Spatulate mandible. 

 Fig. 7. R(4epora Hincksii, n. sp. 7 n, b. Magnified trabecula and celL 



7 c, d. Operculum and mandible, 



Plate VIII. 



Fig, 1. Lepralia Poissonii, Audouin. 



Fig. 2. Anarthropora horrida, n. sp. 



Fig. 3, Phylactella columnaris, n. sp. 



Fig. 4. Lepralia judex, n. sp. 



Figs. 5, 5 a. Smittia murarmata, n. sp. 



Fig. 6. Lepralia mosnica, n. sp. 



Figs. 7, 7 a. Smittia rostriformis, n. sp. 7 b. Lateral view, showing 



avicularium on ooecium. 

 Fig. 8. Membranipora defensa, n. sp. 8 a. Cell, showing junction of 



spines. 



