SHELL OUTER AND INNER STRUCTURES AND RISSOACEAN PHYLOGENY . II . SOME MORE DATA ON THE SHELL STRUCTURES IN MARSTONIOPSIS SCHOLTZI ( A . SCHMIDT , 1856 ) ( PROSOBRANCHIA : RISSOACEA : BYTHINELLIDAE )

In the plfMir lie .ulhor gives smore data on the sheU SEM structures in Mw~ sdNIIzi (A. sc.MDT, 1851), not described by him ••tier. He gives descriptions of lie sheR outer swface and sections perpendlcut. to the growth Rnes. Based on these data and the ones published in his monograph (FALNIOWSKI 1990,thls tolume), the paper is to present some Idea of what possible relationships of Mws~ are.


Introduction
As 1 have already pointed out in my earlier papers (e.g.FALNIOWSKI 1989FALNIOWSKI , 1990 this volume and FALNOWSKI & SZAROWSKA in press), the phytogenetic relationships within the RissOJCeil (•Till¥'8t~• PONDER 1988) are still far from being clear.Obviously, one of the reasons is the low number of the taxonomic characters available.Hence, shell SEM outer and inner structures seem therefore worth of attention as a possible source of new, useful characters.
The data on the shell SEM structures of Jl.fi!rs/oniopSJs schobi (A. SCHMIDT, 1856) (FALNIOWSKI1990, this volume) are Incomplete.since not enough material was available at the lime of the study.MuSl'~ is quite a rare species in Poland (FALNIOWSKI1987).1t Is only recently that it has been possible to complete the description ol those structures In the species.
For technical reasons, it has not been possible to include the plates and descriptions within the monograph (FALNIOWSKI1990, this volume) and, therefore, this addendum appears separately.

Protoconch outer surface
The protoconchs in all the studied specimens were more or less corroded, so no photographs are presented.The surface of the small, uncorroded patches was exactly the same as the one visible on the teleoconch surface described below, bearing characteristic, extremely fine pores approximately circular In shape and not arranged In a net.
Teleoconch outer surface (Rgs. 1 -3) Teleoconch outer surface is macroscopically smooth, only slightly marked growth lines being observable (Ag. 1 ).Under higher magnifications (Ags. 2 -3) the surface Is also smooth, like in  5) it may look compact, with better or worse marked long trabeculae arranged approximately perpendicular to the shell surface (Ag.5), or it may show a fine diagonal structure pattern or be grained In character (Ags.6 -8).Its variable structure Is not of much help in relationships weighting.Within the layer, similarly as In B)'f!JheJ!i1 and ~a'Mif.there are runerous, characteristic cavltal spaces on deep-etched sections (Ags.5 -6 and B).
The transition between the palllsade layer and the palllsade adJoining, Innermost layer Is rather smooth and gradual but it does not form the "transitional layer• that is characteristic of B111}11114 Similarly as In By//JJhela, the innermost layer (Ags.4 -5) Is grained-spongy (may be grainedcompact).Characteristic, fine cavital spaces are present in the layer (Ags.4 -5); similar spaces occur also In B)'f/WJmela and POI81110PJ'f'.{lt.IS: The above resulls seem noteworthy.Although our knowledge of the shell structures in rlssoaceans Is stiD fragmentary, the above data, combined with ones on the shell sections paraRel to the growth Hnes (FALNIOWSKI 1990, this volume), Indicate some possible phytogenetlc Implications.
The shell structures of ~~sxr compared with those of several rlssoaceans (hydroblold and non-hydroblold), Indicate close relationships of the genera: /J}UJi1eJI!6.~~ ~~ Potii110PJ"'~ However, the pore-pattern of Alivs/Ofi/Ops1S Is unique, evidently clfferlng from the uniform net-of-pores pattern that Is characteristic of all the other genera listed above.
The convnon pattern of sheU Inner structure of the four above genera Is actually astonishing.This Indicates that the position of the Lllorldhi14e GRAY, 1857 cannot be as distant from the ~e s.strlcto as suggested by numerous authors.Also the close resemblance of the structures of ~ and i1}UJtJi'lelf6 does not confirm the family rank of the Byf/li1eJiidae GERMA~ 1931.1t is hard to decide, In the Bght of the shell structures data, whether Mrntt1flbps1S is most closely related with iJ).t/1helil or with ~• this also rejects the placement of Mri':WOfi/Ops1S within the BjlhlltNift:fle.Within the four genira considered, the shell tmer structures of ~ and Mri':W~ seem primitive, whHe the ones of ~IIJI7el8 and Pdii110PJtf'l/f/S seem derived.

Acknowledgments
and P~~ and unlike In ~ L:Jiiii'Ae'lf4 R/ssrNr and li't.nCa/e:J'ilOn the surface there are extremely fine pores (arrows In Ags. 2 -3), approximately circular In shape and rather densely arranged, onen In groups, but never forming a regular net characteristic of B.lh).nla.B)'fhhe#irl, f6-rfrobia and POiamopyr.{lt.IS: The pores in Mtmtnt:pS'IS are also apparently smaller than the ones in the former genera.This kind of pores Is unique among the rissoaceans studied so far, since similar pores I have found only In L:Jiilnela but In that genus they were accompanied by big and onen fused pores never found In Mtrst~ Teleoconch sections perpendicular to the growth lines (Rgs.4-8) The main part of the sections perpendicular to the growth lines (Ags. 4 -5) Is filled with columns of the paiNsade layer which are similarly organized In all the Caenopastropoda and, therefore, hardly useful in taxonomy.Between the paUisade layer and perlostracum there Is a thin layer (Ags.5 -8) showing a wide variety of Its structure pattern.Even aner dep etching (Figs 4 -