72 REPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 
used it in the same sense in the paper published by him and Retzius in 
1842, and was followed in this use by Creplin, also in 1842. In 1843 
his article of 1841 wasreprinted in French in Rayer’s Archives. in 
this the German ‘“Psorospermien” is rendered by the French “psoro- 
spermies,” both of them the exact equivalent of the general indefinite 
English plural psorosperms. If anything is needed. to complete 
the evidence it is found in the fact that not one of these observers 
proposed a single binomial name. So it is certain that the term was 
used by Miiller and his immediate successors as a general group term 
and not as a generic designation. And it was so used in 1845 by Dujar- 
din, and in 1851 by Leydig, neither of whom employed a generic name, 
Further, they did not use any specific (binomial) names, all of their 
species, like those of previous authors, being designated as “psoro- 
spermies du brochet,” ‘¢ Psorospermien der Hecht,” or by a similar title. 
The first author to apply the binomial nomenclature to the “ psoro- 
sperms” was Charles Robin. In his Histoire Naturelle des Végétaux Par- 
asites (1853) were collected descriptions and figures of nearly all of the 
previously described forms. Robin there defines the ‘‘ psorosperms” 
as a tribe of Diatoms, as follows: 
Tribus Psorospermez Ch. R. 
Phycoma ex cellulis organicis compositum; cellule albe, fuscx, lutescentes vel 
achromatic. Generatio ignota. (Piscium parasitice.) 
I form this group to receive a certain number of species of parasitic forms 
described first by J. Miiller, and since carefully studied by him, Retzius, and myself. 
From the foregoing it will be seen that to the subclassic (ordinal or 
tribal) name was appended an exceptionally clear definition. In the 
group thus defined Robin placed a single genus, Psorospermia Robin, 
which must, therefore, stand as the type genus of the group. His 
generic definition was: ‘ Characteres tribus.” Robin failed to designate 
any particular species as the generic type. He reproduced descrip- 
tions and figures of 10 forms made known by other authors, under the 
customary headings of “ psorosperms of the pike,” etc. In addition to 
this, however, he inserted a description and figures of a single species 
of his own, which was the only one provided with a binomial name, or 
in other words the only species (in the nomenclatural sense) present. 
Itis plain, therefore, that this species (P. sciane-umbre Robin) must 
stand as the generic type.! 
Curiously enough, however, of all the species collected by Robin 
this is almost the only one which can not be regarded as a myxospo- 
ridian. That it can not be so regarded is evident from a careful exam- 
ination of his definition and figures. Unfortunate as it is that the 
name Psorospermia must henceforth be restricted to organisms having 
1TIn order to place the matter beyond doubt, I now propose to limit the genus 
Psorospermia Robin, as above indicated, viz: to forms of the type of P. sciene-umbre 
Robin, which species I propose as the generic type. I further propose Psorospermia 
as the type genus of Robin’s tribe Psorospermee. 
