The customary phonemic inventory of Russian includes an anomalous segment, the long soft palatal fricative š':. It is anomalous in several respects. It is unique in that other than š':, Russian is not considered to have any phonemically long consonants, although there are other phonetically long consonants (see below), which are customarily and probably best analyzed as a sequence of two “plain” (non-long) consonantal segments of the same type. In addition, while there is a hard palatal fricative š, the long soft š': does not form a hard/soft pair with the hard š the way other pairs of hard and soft consonants (e.g., t/t', s/s', etc.) do. In this respect, too, š': and š are unique; they are the only set of corresponding hard and soft consonant phonemes which is not paired, and distinguishing š from š': as hard vs. soft is not adequate.
Hard š and long soft š': are not phonetically a pair, since they are different in length as well as in the feature hard/soft. They are also not morphophonemically a pair, since they do not alternate in the appropriate environments the way hard/soft pairs do (e.g., brat / o brat'e, but myš / o myše; not *o myš'e, and not *o myš':e). In the Russian phonemic inventory š must be listed as “unpaired” for the feature hard/soft, and š': must also be listed as “unpaired” in that regard.
However, there are other phonetically long consonants in Russian. In almost all cases these arise at morpheme boundaries when a morpheme ends with a given consonant and the next morpheme begins with the same consonant (e.g., pod+d'elat', ras+sv'et, v+vodit', etc.). Because of the concrete shapes of Russian morphemes and their combinability, these phonetically long consonants are typically found among the dentals, palatals and v.
One of the consonants which can occur phonetically long in this way is š:. If there were to be any short/long pairing for š, it would be with this long hard š:, and not with the long soft š':. Correspondingly, if there were to be any hard/soft pairing for š':, it would be with the long š:, and not with the “plain” š. Long hard š: and long soft š': do form a hard/soft pair phonetically, but they do not form a pair morphophonemically, and in that respect they differ from other sets of corresponding hard and soft consonants.
In addition, Russian also has long hard ž: and long soft ž':. Neither of these is of very high frequency, and long soft ž': is especially limited in occurrence. Perhaps because of that, not all speakers have long soft ž': in their phonological inventory, but it still remains for many speakers, including in the normative standard, and probably should be recognized along with long soft š': as a separate phonemic unit.
The paper discusses “pairedness” and the further relations among these “plain” and long consonants, especially among the palatal fricatives, and the implications for the phonological analysis of Russian.