108 MR E. S. CLARK ON 



Pimelodus nigribarbis Boulenger (PI. fig. 3). 

 1 Pimelodus valenciennis Lutken. 



D. I, 6. A. 17. V. 6. P. I, 8. 



This specimen is undoubtedly similar to BOULKNGER'S two type specimens from the 

 Oamapuam Eiver, and described by him in Ann. Mag. Nat. Hist., iv., 6th ser., 1889. 

 It differs from Pimelodus valenciennis, Lutken (Occ. Papers Cal. Acad. Sci., i., 

 1890), in the lengths of anal and adipose dorsal fins. In valenciennis these are equal, 

 but in the Scotia specimen the adipose dorsal is five-sixths of the anal. 



Length of specimen, 167 mms. 



Pimelodus albicans Cuv. and Val. 



Anus albidm, Val., Voy. d'Orb., 1847. 



albicans, Guv. and Val., Hist. Nat. Poins., xv., 1840 (Buenos Aires). 

 Piramutana albicans, Giinther, Ann. Mag. Nat. Hist., 1880, vi., 5th ser. (Rio Plata). 

 Arius moroti, Val., Voy. d'Orb., vi., 1847 (La Plata). 

 Piramutana blofhii, Cuv. and Val. 



Pimelodns albicans, Eigenmann and Eigenmann, Proc. Cal. Acad., i., 1890 (Rio Plata). 

 ,, ,, Eigeumann, Proc. Wash. Acad. Sciences, March 4, 1907. 



D. I, 6. P. I, 10. V. 6. A. 11. 



EIGENMANN'S description in Proc. Cal. Acad., 1890, adequately covers the 

 characteristics of the Scotia specimen. There are no pterygoid teeth, and those on 

 the palate are reduced to two small separate patches on the vomer. The maxillary 

 barbel reaches the root of the caudal fin, " as in young specimens 6 to 8 inches long, 

 though it reaches only to the anal fin in specimens 10 inches long" (GUNTHER). 



Length of specimen, 235 mms. 



Plecostomus laplatse Eigenmann (PI. figs. 1 and la). 

 Plecostomus laplatse, Eigenmann, Proc. Wash. Acad. Sciences, March 4, 1907, 



D. I, 7. A. I, 14. 



The two specimens are certainly EIGENMANN'S laplatte, described by him in 1907 

 as a new species. The number of scutes in a longitudinal series is 31 + 1 caudal scute. 

 Smooth patches between pectoral and ventral are well marked. Head and abdomen 

 are covered with small dark spots, while anterior part of body has larger spots. Fins, 

 except caudal, spotted. Alternating pale and dark longitudinal bands on body. 



Two specimens. Lengths, 283 and 420 mms. 



Prochilodus argenteus Agassiz. 



P. argenteus, Cuv. and Val., xxii. (Rio San Francisco, Brazil). 

 Giinther, B.M. Cat., v. (Brazil). 



n_ i A 



D. 11 (12). A. 10, Lat. line 45, lat. trans v. . 



Six excellent specimens were brought back by the Scotia. They average in length 



