QUESTION OF NOMENCLATURE 35 



P. viridis (L). p. 21. 



P. marmorata n. s. p. 21. * 



P. biocularis (L.) p. 22. 



P. sulcata n. s. ( — Mytilus exustus L.) p. 22. 

 Melina n. g., p. 22. 



M. semiaurita (L.) p. 22. 



M. perncB/ormis n. s. {=Ostrea Perna L.) p. 23. 



M. Isogonum (L.) p. 23. 



M. Ephippitim (L.) p. 23. 

 It will be seen from the foregoing that there are quite a 

 number of names that are by some authors referred to one author- 

 ity and by others to another. The question is therefore of some 

 importance. Inasmuch as most of my study has been upon the 

 freshwater mussels and, as a consequence, I am more familiar 

 with the literature of the Unionidae than with any other mol- 

 luscan family, and as an important genus of the Unionidae is 

 described in the thesis in hand, I will take the part for the whole 

 and deal with the authorship of Unto. In order to state properly 

 the problem confronting us, I shall quote from various authors, 

 published and manuscript regarding the authorship of Unto: 



1. "Genus UNIO Retzius. 



" It seems impossible to ascertain with certainty who is the 

 author of this genus. In 1788, Laurentius Miinter Philipsson 

 described it in a thesis delivered under the presidency of his master, 

 Retzius, [reference] at the University of Lund, in Sweden, at a 

 public examination for a doctor's degree. Whether Philipsson 

 or Retzius should be credited with the genus can not be positively 

 known, as it is believed by some that the master was the author 

 of the dissertation, which the student merely defended. I am 

 inclined to take this view of the matter, for the reason that Retzius 

 was an author of repute, while it is not known that Philipsson 

 ever gave any attention to natural history or was the author of 

 any genera or species before or since." — Simpson, Charles T., 

 in The Classification and Geographical Distribution of the Pearly 

 Fresh-water Mussels. Proc. U. S. Nat. Mus. XVIII: 300 [1896]. 



2. "This genus was described in a thesis by Laurentius 

 Miinter Philipsson under his master Retzius, in the University of 

 Lund, Sweden, and it is often credited to the former. I am in- 

 formed by Professor Joh. Chr. Moberg, of Lund, that by a former 

 law or custom of the University, the professor was considered the 



