eigenmann: the cheirodontin.^. 5 



do not differ greatly from the other species. The caudal lobes may be a little 

 longer or shorter, a little more pointed or rounded, and there may be more or less 

 difference between the upper and lower lobes, but there is no striking deviation 

 from the type. The ventrals and pectorals may be a little longer or shorter, but 

 here again there is no great divergence from the central type. The scales differ 

 materially. The lateral line may be developed on but two scales, or it may be 

 complete. It is complete in Probolodus, Parecbasis, Holesthes, and Odontostilbe. 

 It is almost complete in Microschemobrycon. In the other genera it is developed 

 on less than fifteen scales, the exact number varying with the species. In Grundulus 

 the predorsal scales have disappeared; in Aphyodite the caudal has become mostly 

 covered with small adherent scales, and in Compsura and Odontostilbe hastata 

 the male s provided with a few enlarged scales on the caudal which recall the 

 Glandulocaudinse. The degree of the development of the pseudotympanum differs 

 greatly, the humeral region being apparently normal in a number of species. It 

 is most highly developed in Holesthes, Odontostilbe, Megalamphodus, and the deeper 

 species of Cheirodon. In color (alcoholic, which means the distribution of melano- 

 phores only) the species of this subfamily do not differ greatly from species of 

 Heniigrammus and Hyphessobrycon of the Tetragonopterinse. In many species 

 of the Tetragonopterinse and other subfamilies some sort of a spot occurs on the 

 sides, a little behind the origin of the lateral line. This spot is found in over half 

 of the species with tricuspid teeth. In the species with multicuspid teeth it occurs 

 only in Mixobrycon. A caudal spot at the end of the caudal peduncle and on the 

 base of the caudal has an even wider distribution among the Characins in general. 

 Among the Cheirodontinse it is all but uniformly found in the species with multi- 

 cuspid teeth, i. e., in those species in which the humeral spot is not developed. 

 Other markings are some sort of a spot on the dorsal, which occurs in six species 

 belonging to four genera. It is therefore not a sign of relationship. Similar spots 

 occur on some of the smallest Tetragonopterids. Another marking which occurs 

 sporadically in several species is a dark band along the tips of the short anal rays 

 and across the lobe of the anal. 



Deviations from the generalized type on which the genera are based. — The frontal 

 fontanel may be small, having the form of an equilateral triangle, and may form 

 only a wedge between the posterior part of the frontals (it has nearly reached the 

 vanishing point in Aphyocheirodon) or it may, as in Megalamphodus, be of nearly 

 uniform width and entirely separate the frontals. 



In all but three genera, Grundulus, Spintherobolus, and Mixobrycon, the second 

 suborbital is in contact with the preopercle below. In both Grundulus and 



