SOTALIA TUCUXI. 19 



Besides the original descriptions of the different species, we Lave 

 batterer's account of a specimen of river-dolphin harpooned at the 

 mouth of the Eio Negro.* The specimen, which was a male, is repre- 

 sented as having been ashy-gray above and violet-gray below, with fins 

 colored like the back. In coloration, therefore, it agreed tolerably well 

 with S.Jluviatilis. Natterer gives a number of measurements, but we 

 have only the measurements of S. hrasiliensis with which to compare 

 them. From these it appears that the latter species has shorter pectoral 

 fins, higher dorsal fin, and narrower flukes than had batterer's specimen. 



These differences give some strength to the opinion that the marine 

 species, S. hrasiliensis and 8. giiianensis, are distinct from the fresh- water 

 species. 



Von Pelzeln is inclined to support Gray's opinion that all the nom- 

 inal river species are identical. He states, however, that Bates men- 

 tions 8. pallida as occurring in the lower Amazon, which does not appear 

 to be a fact. Bates's words are as follows : 



Iq tlie upper Amazous a third palo, flesb-colored species is also abiiudaut (tlie 

 Delphinus pallidus of Gervais).t 



The species which he found at the mouth of the Tocantins Eiver is 

 the ^^Stcno tucuxi of Gray." 



In this unsatisfactory condition our knowledge is, unfortunately, 

 likely to remain, until more material has been collected. The skeletons 

 of a number of adult individuals, and observations upon the variation 

 of the color and of the proportions of the pectoral and dorsal fins among 

 members of the same school, are requisite to solve the problems which 

 these five nominal species present. 



Skulls Nos. 1189a, S , and 1189&, $ in the British Museum, the types of 

 iS. tucuxi are those of young animals, as is indicated by the exposure of 

 a considerable portion of the frontal behind the maxilla and the dis- 

 tinctness of the occipito-parietal suture. The intermaxillte are short 

 proximally, and the maxilhie are visible on the anterior and lateral 

 margins of the anterior nares. The ridge of the mesethmoid is higher 

 than the triangular prenarial area in its middle part, and is thickened, 

 forming a transverse ridge. The intermaxilliTi are broadest and quite 

 flat near the middle of the rostrum. The prenarial triangle is concave. 

 The nasals are small in the male, and present only a thick upper edge. 



The inner margins of the pterygoids in this specimen are separated 

 at the extremity by an interval of about 28™'" and at the base are about 

 fjmm iipart. The outline of these bones in the two sexes is somewhat 

 different. The intermaxillai and vomer appear in the median of the 

 palate anteriorly in No. 1189 a for a distance of about IIG'"". The 

 crowns of the teeth are tinged with brown, the roots are open. The 

 ramus of the mandible is flat internally. 



A skull recently purchased by the National Museum agrees very 



* Brasilische Siiugetbicre. Resultate von Joliauu Natterer's Reisea ia den Jabren 

 1817 bis 1835. Dargcstelltvou August vou Pelzeln. Wien, 1883. Pp. 95-96. 

 t Bates, Naturalist oa tbe Amazous, 1364, p. 83. 



