232 Fretp Museum or Natura. History — Zoéiocy, Vor. X. 
canensis, Lasiancistrus planiceps and Loricaria capetensis, all 
originally described in one of our preliminary papers (1913), remain 
peculiar to this stream. The last two, however, have very near relatives 
on the Atlantic slope of Colombia. 
The families Pygiditde and Cyclopide are each represented by a 
single species; both are described as new in our preliminary paper 
(1913). This in both instances represents the northernmost record for 
these families. The Panama representatives have very near relatives 
in Colombia. 
In the family Characide there are the following species that appear 
to be peculiar to the Rio Tuyra; Apareiodon dariensis, Creagrutus simus 
and Hemibrycon dariensis sp. nov. While distinct, all have near 
relatives in Colombia, and may therefore be regarded as among the 
latest migrants. Phanagoniates macrolepis, Piabucina feste and Hoplias 
malabaricus do not occur in other streams of Panama, but their range 
extends southward into Colombia or beyond. The rest of the repre- 
sentatives of this family are found in other streams of Panama and 
five of them occur also in the Rio Chagres, viz.; Astyanax ruberrimus, 
Bryconamericus emperador, Gephyrocharax atricaudata, Compsura gor- 
gone and Pseudocheirodon affinis gen. et sp. nov. Only the first one 
of these is known from south of the Rio Tuyra. Brycon striatulus, - 
Brycon argenteus and Thoracocharax maculatus also appear to reach the 
southern extreme of their range in the Rio Tuyra. They, however, 
possess very near relatives in Colombia. The genus Brycon seems to 
be yielding to the effects of different conditions, and now consists of 
several rather closely related species. 
In the family Gymnotide, Sternarchus rostratus seems to be com- 
mon to the Rio Tuyra and the Rio Atrato. Sternopygus dariensis sp. 
nov. is limited to the Rio Tuyra Basin. The other two species are of 
wide distribution. EHigenmannia virescens, however, is not known 
north of the Rio Tuyra. 
The Paciliide are comparatively rare in this river basin and the 
species are few. Mollienisia caucana reaches its northern limit of dis- 
tribution in the Rio Tuyra; the variety Priapichthys tridentiger cana 
seems to be peculiar to this stream; and Priapichthys dariensts is 
known from this river basin and westward on the Pacific slope of 
Panama. 
In the family Cichlide there is a single species, Cichlasoma umbri- 
ferum, that seems to be peculiar to this stream. Cichlasoma tuyrense 
and Cichlasoma calobrense are common to this stream and the Rio Ba- 
yano. The other two species of this family are of rather wide distribu- 
tion and occur on both slopes of Panama and southward. 
