Zoological Society. 59 



lis, I think it best to connect with the description a revision of the 

 whole Family to which it belongs. 



Petromyzonid^. 



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



Lampredia, Rafin. Anal. Nat. 94, 1818. — Petromt/conidce (Petro- 

 myzonini), Bonap. Svst. Ichth. 1838 ; De Kay, Nat. Hist, of New 

 York, 3 79. — (Fam.) 'Hyperoartia, Mull. Abhandl.Akad. Berlin, 1836, 

 77 ; Mag. Zool. & Bot. i. A<i&.—Petromyzidie, Gray, Syn. B.M. 1842, 

 148, 150. 



Miiller {Ahhandl. 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. 



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. 



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

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

 Imgual teeth elongate, conical, arched. 



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

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

 most largest ; Imgual 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. 



6. 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. 



B. Ammoccetina. Teeth none ; eyes hidden. 



7. Ammoc(etes. 



A. Petromyzonina. Teeth distinct. 



1. PETROMYZON. 



Upper inner teeth two, triangular, close together. Lower inner 

 tooth single, large, crescent-shaped, many-toothed. Labial teeth 

 conical, acute, numerous, in diverging, arched series ; the inner one 

 largest, and gradually becoming smaller near the edge. Tongue with 

 two compressed, pectinated teeth above, and a broad, lunate, deutated 



