BEITISH PAL^OGENE BETOZOA. 243 



In regard to Adeonellopsis, it seems to me absolutely necessary to accept that or Busk's 

 [No. 8, p, 178J Reptadeonella, as it is going rather far to place such a species as 

 '■'■LefTctlia " violacea, Johnst., in Adeona or Microporella. Rei)tadeonella is prior by two 

 years, but it was based only on zoarial characters and was never properly diagnosed, 

 and I therefore prefer to accept Macgillivray's better defined genus [No. 2, pt. ix. 

 p. 134, and No. 3, p. 210]. 



Reuss has described another species which it is necessary to consider in connection 

 with the Microporellidse, as it possesses both a trypa and an oral sinus. The species 

 which shows this feature is of such interest in connection with the evolution of this 

 group that it is advisable here to diagnose the new genus necessary for its reception. 



Schismoporellai, n. g. 



Diagnosis. Zoarium lepralian or escharine. 



Zooecia elongate, oblong (in known species). Aperture orbicular, with a large sinus. 

 The front wall has a zooecial pore. 



Ocecia external, globose. 



Type species. Schismoporella scMzogaster (Reuss)^, 1847, Helvetian, Austria. 



This genus may at first throw doubt upon the assumed homology of the sinus and 

 trypa, the latter being regarded as the more specialized. The occurrence of Schismo- 

 forella may, however, be explained by a repeated formation of a sinus after the zooecial 

 pore has travelled well away from the peristome : or else the division of the trypa 

 into two or more pores has very frequently taken place, and there seems no impro- 

 bability in one of these parts persisting as a sinus. If neither of these explanations is 

 correct, then Schismoporella is probably a primitive form uniting characters now divided 

 between two families. 



The following synopsis summarizes the classification of this group that is here 

 proposed: — 



Schizoporellidte : schizostomatous. External ooscia. 

 Adeonellidce : primary aperture schizostomatous. Gonoecia. 



( Adeonince : with r Zoarium fenestrate, &c. Adeona. 



gonoecia. \ „ foliaceous or encrusting. Adeonellopsis. 



Microporellinece : = Mici-oporella, Tessarodoma, &c. 



trypa present, 'i external marsupia. 



I Sclmmoporellince : — Schismoporella. 



\^ with trypa and sinus. 



' i'rom a\i(rfj.a, a slit, and wopos, a pore. 



^ Cellepora scMzogaster, Keuss, 1847, No. i, p. 84, pi. x. fig. 9 ; Mollia schizogaster, D'Orbigny, .No. 2, 

 p. 388 ; Lepralia scMzogaster, Eeuss, No. 14, p. 161, pi. iii. flg. 10. 



VOL. XIII. — PART VI. No. 4. — June, 1893. 2 Br 



Schiso- 

 thyriata. 



< 



MicroporellidoK : 



i 



