110 NOMENCLATURE OF THE LAMPREYS-GILL. 



the cliaracter used to distinguish them is not of equal value with the 

 union or separation of lower pharyngeal bones and like modifications 

 generally used. 



ORTHOGRAPHY. 



In common with almost all other zoologists, 1 have used the name 

 Petromyzontidcc for the lampreys. It only lately occurred to me that 

 the form was a suspicious one at least, and, on investigation, I have been 

 obliged to believe that it was due to a false analogy. Certainly the 

 analogous Greek word /j.u^w,' has !J.b:w'^i,q in the genitive, and the cor- 

 responding Latin equivalents are myxon and myxonis. The first to 

 use the form Fetromyzontidxe appears to have Deen Prof. Agassiz, in 

 1850, in Lake Superior (p. 249), and the Edinburg New Philosophical 

 Journal (v. 49, p. 242). It is probable that he was led to this form, 

 without sufficient reflection, by being misled by analogy with words 

 ending in — odon ( Tetraodon, Diodon, etc.). Bonaparte had long before 

 given the better form, Fetromyzonidce, and this should be revived. 



EXOMEGAS. 



The genus Exomegas^ proposed in 1882 (Proc. U. kS, Nat. Mus., v. 5, p. 

 524) for the Petromyzon macrostomus of Burmeister, has been justified by 

 the recent publication of a memoir on the species by Dr. C. Berg,* who 

 has, however, referred it to the genus Geotria. I have recently called 

 attention in Science for January 19, 1894 (v. 23, p. 30, "A South 

 American lamprey"), to certain discrepancies between the description 

 and figure and the advisability of reexamining the animal. 



A detailed comparison of the contrasting skeletal peculiarities of 

 Petromyzon and Lampetra is very much needed. It may be hoped that 

 Prof. Gage will extend his investigations and give us the requisite 

 information. 



*Anales del Museo de la Plata [etc.]. Seccion zoologica I. Geotria macrostoma 

 (Burm.) Berg y Thalassophryiie moutevideusis Berg. — Buenos Aires — 1893. 



