72 REPORT OF THE COMMISSIONER OF FISH AND FISHERIES. 



used it in the same seuse in the paper publislied by him and Retzius in 

 1842, and was followed in this use by Creplin, also in 1842. In 1843 

 his article of 1841 was reprinted in French in Eayer's Archives. In 

 this the German "Psorospermien" is rendered by the French "i)Soro- 

 spermies," both of them the exact equivalent of the general indefinite 

 English plural ][)sorosperms. 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 WatureUe des Vegetaux 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 Psorosperraere Ch. R. 



Phycoma ex cellulis organicis compositura ; celluhe albaj, fuscie, Intescentes vel 

 achromaticfe. Geueratio ignota. (Piscium iiarasiticie.) 



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 tlie 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 i^ike," 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. 

 It is plain, therefore, that this syteciea {P. scia'itw-umhrw Hohiu) mast 

 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 Psorospei^mia must henceforth be restricted to organisms having 



1 In 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. scmnce-umbrce 

 Robin, which species I propose as the generic type. I further propose Psorospermia 

 as the tyjie genus of Robin's tribe Psorospermece, 



