PROCEEDINGS OF THE NATIONAL MUSEUM. 109 



Geuus LAMPETRA. 



"il lampreda, KAKiNESQrE, Analyse tie la Natiiif, ]•. 9\ (without description or 

 typonym), 1815. 



?? Pricus, Rakinesquk, Analyse tie la Nature, i». 04 ( without descrijition or typo- 

 nym), 1815. 



;^ Lampetra, (Jkay, Pror. Zool. Soc. Londtni, pt. 19, jip. 235, 237, 1851; List Speci- 

 mens P'ish Brit. Mus., pt. 1, p]). 1.37, 140, pi. 1, f. 2 (mouth)^ 

 1851. 



? *'co?ecosoma, GiHARD, Expl. anil Surveys for R. R. Route to Pacitic, Of., v. 10. 

 Fishes, \y. 384, 1858 (based ou larval form). 



= Peiromyzon, Malm, Forhandl. Skand. Naturf., 8. mode, p. 580, 18H0. 



=- Ammocoeks, Gill, Proc. U. S. Nat. Mus., v. .5, p. 523, 1883. 



Petromyzon sp. aucf. pi. 



Ichthyomyzon sp., Girard. 



FAMILIES. 



In 1870 Dr. (riinther united tlie genera Caragola and Mordacia of 

 Gray, the former of which was based on specimens with the hiteral 

 corneous lamelhe preserved, while the latter was founded on a specimen 

 in which they were lost and only exhibiting- a single papillary prom- 

 inence for each. For the combination he prefered the second name of 

 Gray (Mordacia), based on a mutilated individual. In 1882 I used in 

 preference the first name {(Jaragola), based on a perfect individual. I 

 have since been led to believe that the precedence of one name by such 

 a little margin as Carayola has over Mordacia has no value, and that 

 aptness of diagnosis, however desirable, is not necessary to secure prior- 

 ity, and I have therefore followed Dr. Giinther in accepting the name 

 Mordacia instead of Caragola. I have also deemed it proper to elevate 

 the subfamily Caragolinw to family rank, and named it Mordaciidct'. 

 Eeferences follow. 



Family M o r d A o 1 1 d .e . 



= Carayolimr, Gill, Proc. U. S. Nat. Mus., v. 5, p. 524, 1882. 

 =^ Mordaciida', Gill, Mem. Nat. Acad. Sc, v. 6, p. 129, 1893. 

 Petromyzontidw pt., auct. pi. 



Hyperoartia with two distant lateral tuberculigerous laminse devel- 

 oped from the upper arch of the annular cartilage. 



The only known genus is Mordacia. 



With this is to be contrasted the family FctroMyzonidw as thus 

 restricted, viz: 



Family Petromyzonid^. 



< Petromyzoniida', Gill, Proc. U. S. Nat. Mus., v. 5, p. 521, 1882. (Full syn. given.) 

 = Pelromyzontidw, Gill, Mem. Nat. Acad. Sc, v. 6, p. 129, 1893. 



Hyperoartia with a single median tuberculigerous suproral lamina 

 developed from the upper arch of the annular cartilage. 



It behooves those who may object to these families to consider why 



