Vohjzoa of Mauritius. 83 



dichotomous. Zooecia rhomboidal, opalescent, glistening, 

 granulose, not punctured ; older zooecia immersed, the orifices 

 of the separate cells alone being visible ; primary orifice oval 

 (long diameter transverse) ; peristome with a slit-like fissure 

 terminating in a round pore ; on one side of peristome a small 

 avicularium with small hemispherical mandible. Dorsal sur- 

 face glistening, granulose, divided into irregular areas by- 

 raised lines. Ooecia long, oval, depressed, marked with a 

 broad, median, beaded band, narrowing superiorly to a slight 

 ridge, Chitinous appendages. 



Family Tubuliporidae. 



Genus Idmonea. 



Idmonea radicata, n. sp. (PI. IX. fig. 2.) 



Zoarium about -^ an inch high, ramose, branches flattened, 

 subdichotomous, anastomosing, giving off cylindrical calca- 

 reous processes, fixing it to the base from which it grows ; 

 anterior surface hyaline, finely punctured. Zooecia in pairs in 

 younger, and threes in older parts of branches, forming sub- 

 parallel alternating rows ; zooecia closely connate for about 

 half their length, then diverging, curved so as to be concave 

 downwards, increasing in height from within outwards ; 

 dorsal surface flat, faintly marked with transverse concentric 

 rings of growth, finely punctured and marked with fine paral- 

 lel longitudinal striee. Ooecia anterior, formed by an infla- 

 tion of the branch ; surface punctured ; four or five zooecia 

 subimmersed. 



Idmonea torUiosa, n, sp. (PI. X. fig. 2.) 



Zoarium erect, flattened, branching dichotomously, branches 

 subtriangular. Zooecia in two or three series, increasing from 

 within outwards, large, free only for a quarter of their length ; 

 punctured both in the adnate and free portions. Dorsal sur- 

 face covered by thick, punctured, tortuous, intertwining tubes. 

 Ooecia ? 



In this form aborted zocecia instead of forming radical 

 tubes, as in some species, are closely adpressed to the dorsal 

 surface of the zoarium. 



Genus HOENERA. 

 Hornera s'pinigera^ n. sp. (PI. X. fig. 1.) 

 Zoarium flabellate, irregularly pitmate j branches cylin- 



