198 Mr. C. T. Regan— ^ Synopsis of the 



Exomegas macrosiomus, Gill, Proc. U.S. Nat. Mus. v. 1882, p. 624 ; 



Berg, Oommun. Mus. Buenos Aires, i. 1899, p. 91. 

 Geotria macrostoma, Berg, Ann. Mus. La Plata, Zool, i. 1893, p. 3, 



pi. i. 

 Geotria macrostoma, var. gallegensis, Smith, Bih, Svensk. Vet.-Akad. 



Handl. xxvi. iv. no. 13, p. 26, pi. iv. 



Argentina; Patagonia. 



Recent descriptions show that tliis species is a true Geotria ; 

 the supraoral lamina appears to have the same form as in the 

 other species of the genus ; the infraoral himina is absent or 

 deciduous, but this may be the case in G. australis also ; the 

 so-called enlarged outer series of teeth seem to be the fringes 

 of the disc. 



3. Peteomyzon. 



Petromyzon (part.), Linn. Syst. Nat. ed. 10, p. 230 (1758) ; Giinth. 



Cat. Fish. viii. p. 500 (1870). 

 Petromyzon, Gray, Chondropt. p. 143 (1851). 

 Bathymyzon, Gill, Proc. U.S. Nat. Mus. 1883, p. 254. 



Disc covered with radially arranged teeth. A single 

 narrow bicus];id supraoral lamina; infraoral lamina cuspi- 

 date. Anterior lingual lamina with two curved denticulated 

 ridges separated by a median longitudinal groove. Dorsal 

 fins separate. 



North Atlantic and Mediterranean, entering rivers. 



1, Petromyzon marinus. 



Petromyzon nnarhmSjlAum. Syst. Nat. ed. 10, p. 230 (1758) ; Giinth. 



Cat. Fish. yiii. p. 501 (1870) ; Day, Fish. Brit. ii. p. 356, pi. clxxviii. 



(1884) ; Jord. & Everm. Bull. U.S. Nat. Mus. xlvii. 1896, p. 10; 



Berg, Bull. Imp. Acad. St. Petersb. (5) xxiv. 1906, p. 176. 

 Bathymyzon hairdii, Gill, Proc. U.S. Nat. Mus. 1883, p. 254 ; Jord. & 



Everm. t. c. p. 9. 

 Petromyzon dorsatus. Gage, Wilder Quarter Century Book, p. 425, 



pis. i., iii., & vi. fig. 19 (1893), 

 Petromyzon marinus unicolor, Jord. & Everm. t. e. p. 9. 



Infraoral lamina with 7 to 9 cusps ; 4 inner labial teeth on 

 each side enlarged^ bicuspid. 



North Atlantic and Mediterranean, entering rivers in 

 Europe and North America. 



1. 780 mm. . Dr. F. Day. 



2. 600 mm. Baltic. Haslar Coll. 



3. 210 mm. Scotland. Dr. Johnston. 



4. 550 mm. Lough Neagh, R. Patterson, Esq. 



5. 630 mm. Devonshire. 



6. 800 mm. . London Market. 



7. 620 mm. Holland, Lidth de Jeude Coll. 



