Fish-fauna of the Rio de la Plata. 9 



9. Micropogon ornatus, Gthr. \_Ch.~\ 



10. Micropogon undidatus, L. 



11. Pogonias fasciatus } Lac. 



12. Pachynrus furcroeus, Lac. (=Corvina Gillii, 



Steindachner, 1867). 



13. Atherinichthys bonariensis, C. & V. 



14. Atherinichthys argentine?isis, C. & V. 



15. Mugiljjlatanics, sp. n. 



D. 4 | J-. A. f. L. 1. 38. L. tr. 15. 



The height of the body is a little more than the length of 

 the head, which is one fourth of the total (without caudal) . 

 The snout is broad, the width of the interorbital space being 

 half of the length of the head. Eye with ft thick and 

 broad adipose membrane ; lips thin. The prgeorbital leaves 

 only the extremity of the maxillary uncovered. Cleft of the 

 mouth twice as broad as deep ; the angle made by the ante- 

 rior margins of the mandibles is obtuse. The first dorsal 

 spine scarcely longer than the second, and half as long as the 

 head ; it is a little nearer to the end of the snout than to the 

 base of the tail. Anal and dorsal fins not scaly ; the pectoral 

 fin terminates opposite to the eighth scale of the lateral line ; 

 base and posterior margin of the pectoral blackish. 



Six specimens from Buenos Ayres, the largest being 18 

 inches long. 



Anacanthini. 



16. Solea Jenynsii, Gthr. ( = Achirus Lorentzii, 



Weyenbergh). 



17. Aphoristia ornata, Lac. [Ch.] 



Malacopteeygians. 



18. Platy stoma Orbigniamcm, Val. 



19. Piramutana albicans (=Arius albicans, C. & V. ; 



= Ariusalbidus,Ya\. } =Arms moroti, Val., 

 nec= Piramutana Blochii, C. & V.). 



Tn this species pterygoid teeth are constantly absent, the 

 teeth on the palate being reduced to two small separate groups 

 on the vomer. There is no doubt whatever of our specimens 

 being identical with those obtained by D'Orbigny in the 

 Rio de la Plata ; therefore Miillcr and Troschel were 

 wrong in identifying this fish Avith the Silurus clarias of 

 Bloch. The fish described by Liitkcn as Pseudariodes albi- 



