26 FISHES FROM BRAZIL 



83. Sciadeichthys proops (Cuvier and Valenciennes). 

 Two specimens were collected in the Para market, and one at Ceara. 

 84. Selenaspis herz'bergii (Bloch). 



This was by far the most abundant of the subfamily Tachisurinae in 

 the market at Para during our stay. The patch of teeth that develops be- 

 hind the palatine patch and forms the "backward projecting angle" may be 

 found in all stages of development. Sometimes it is not present at all ; 

 sometimes it forms a small disconnected patch ; sometimes it is very large, 

 connected with the palatine patch, and extends well back in the roof of the 

 mouth. All intergradiations are present. It is not altogether a develop- 

 ment of age or size as has been supposed, for it may be better developed 

 in a specimen 8 inches long than in one a foot long, while other specimens 

 of similar sizes, differing from these in no other manner, may or may not 

 have it developed. However, it is usually best developed in large specimens, 

 while specimens 7 or 8 inches long only occasionally have it. 



There is considerable variation in the roughness of the top of the head, 

 and of the sharpness of the median ridge on the occipital process. One or 

 two specimens were seen with a narrow but very evident groove running 

 back from the frontal but not reaching to the occipital plate. 



85. Tachysurus nuchalis (Gunther). 



A few specimens were taken at Para which differ from the description 

 of the type in having the maxillary barbels extend scarcely to the middle of 

 the pectoral spine instead of "nearly to the end." The tooth-patches on the 

 palatines are the shape and size figured by Dr. Giinther, and the palatine 

 teeth are coarse. The inner mandibular teeth are coarse and all of the 

 teeth are brown-tipped. The gill membrane forms a distinct free fold 

 across the isthmus, thus differing from Tachysurus spixi. 



86. Pimelodina flavipinnis Steindachner. 



Three specimens, from 12 to 15 inches in length, were taken at Para. 

 The maxillary barbel in the large specimen reaches only to the end of the 

 adipose dorsal, thus agreeing with Pimelodina nasus Eigenmann. In the 

 other two it reaches to or a little beyond the caudal base, as described for 

 Pimelodina flavipijinis. The length of the adipose fin is from 2^4 to 2^ 

 in the length, thus coming about between these two species. The inter- 

 orbital space is convex, and the head behind the eyes is not compressed as 

 in Pimelodina nasus. The eye is contained about twice in the interorbital, 

 or nearly midway between the condition described for these two species, as 



