259 



support the nieinhranous \v;ill. Tlic losette-plalos are disposed in a very scattered 

 row near tlie lateral ridge. 



With regard to the appearance of the various lateral chaud)ers on the hi- 

 zocecial internode reference may be made to the figures and the accompanying ex- 

 l)lauation of the plates. 



Ooecia were not found in liie fragment examined. 



Form of colony. In the examined fragment two bi-zooccial inlernodcs often 

 succeed each other and also rows of up to four single zoa?cia. 



Of this species I have had the opportunity of examining a dry fragment of 

 Wyv. Thompson's original s]iecimcn from Bass Straits (British Museum). 



The genera Stenostomaria and Ditaxipora set np by Mac Gillivray' arc 

 closely related to Strophipora, and in both of them the whole or almost the whole 

 of the surface of the zooecium is occupied by the lateral chambers. Both genera 

 contain only a single species, and in Ditaxipora internodia Waters, the internodes 

 of which consist of 7 — 8 zooecia disposed in two alternate rows, the greater part 

 of the basal surface, judging from the figures, is formed by a single (outer) pedal 

 chamber. The same author has founded the genus Microstomaria - on a single 

 bi-zo(Kcial internode, and the longitudinal ridge represented in tig. 29 seems to 

 show that this genus must also be related to Strophipora. 



Family Onchoporidae. 



The slightly calcified zoa'cia, the frontal surface of which is covered by a 

 closely adhering (chitinous?) membrane, are generally provided with a number 

 of superficial, uni- or multiporous rosette-plates, which are most often situated 

 in the distal part of the zooecium. The distal wall, which is bent from side to 

 side, has a number of uniporous or one multiporous rosette-plate, while the dis- 

 tal half of each lateral wall has a single multiporous plate. No aviciilaria. The 

 strongly projecting hyperstomial oa'cia, the aperture of which may be closed by 

 the zooecial operculum, consist of two membranous (chitinous?) layers, between 

 which there is a cryptocyst layer, which springs from the distal wail. Free, 



branched colonies. 



Synopsis of the genera. 



1) The compensation-sac opens outwards through a crescentic ascopore. 



2) The zooecium consists of three dilTerent segments: a short proxi- 

 mal, a long stem-like middle and a widened distal one; (the operculum 

 compound or simple) Calwellia W. Thomps. 



' 76, pp. 16 and 22. ' 76, p. 18. 



17* 



