235 



12. Description of a new form of Lamprey from Austra- 

 lia, WITH A Synopsis of the Family. 

 By J. E. Gray, Esq., F.R.S., V.P.Z.S. etc. 



(Pisces, PI. IV. V.) 



The Lamprey which I have now to present to the attention of the 

 Society differs in so remarkable a degree from any other known spe- 

 cies, that, premising that I propose for it the name of Geotria Austra- 

 lia (Pisces, PI. v.), I think it best to connect with the description a 

 revision of the whole Family to which it belongs. 



PeTROMYZONIDjE. 



Nasal aperture closed, and the palate entirely covered with skui. 



Lampredia, Rafin. Anal. Nat. 94, 1818. — Petromyzonidee {Petro- 

 viyzonini), Bonap. Syst. Ichth. 1838 ; De Kay, Nat. Hist, of New 

 Xoxk,2,79.—{Fam.) Hyperoartia, Miill.Abhandl.Akad. Berlin, 1836, 

 77; Mag. Zool. & Bot. i. 406. —PetromyzidcE, Gray, Syn. B.M. 1842, 

 148, 150. 



Midler (Abhandl. Akad. Berlin) divided the genera thus : — 



1. Petromyzon, with visible teeth. 



2. Ammocoetes, without visible teeth. 



Synopsis of Genera. 

 a. Petromyzonina. Teeth distinct ; eyes visible. 



1 . Petromyzon. Upper inner teeth two, conical, close together ; 

 lower single, crescent-shaped ; labial teeth numerous, conical ; lin- 

 gual teeth two, pinnate (PI. IV. f. 1). 



2. Lampetra. Upper and lower teeth transverse, crescent- 

 shaped ; labial teeth in two submarginal rows ; inner lateral teeth 

 larger, two- or three-lobed, lingual teeth pectinate (PI. IV. f. 2). 



3. Geotria. Upper and lower teeth transverse, crescent-shaped; 

 upper lobed ; labial teeth numerous, distant, acute, innermost largest ; 

 lingual teeth elongate, conical, arched (PI. IV. f. 3). 



4. Velasia. Upper and lower teeth transverse, crescent-shaped ; 

 upper two-lobed ; labial teeth numerous, crowded, truncate ; inner- 

 most largest ; lingual teeth elongate, arched. 



5. Caragola. Upper internal teeth two, far apart, three-lobed; 

 lower crescent-shaped, nine-lobed ; labial teeth transverse, band-hke, 

 four tubercles ; lingual teeth flattened (PI. IV. f. 5). 



(3. MoRDACiA. Upper inner teeth two ; lateral three-lobed ; lower 

 nine, conical, in an arched series ; labial teeth conical, in a single sub- 

 marginal series ; lingual teeth elongate, conical, arched (PI. IV. f. 6). 



B. Ammocoetina. Teeth none ; eyes hidden. 

 7. Ammoc(etes. 



