November 3, 1905.] 



SCIENCE. 



561 



together in the same neighborhood. It is, 

 however, possible that the isolation of a 

 part of the reef or even of that of a single 

 coral head might in long periods serve the 

 same purpose. 



Enneapterygnis is a genus of blennies in 

 size and distribution closely parallel with 

 Eviota. It contains species of moderate 

 size found in the Gulf of California, in 

 New Zealand, the Red Sea and Japan. 

 In these same coral heads, species of this 

 genus also occur, all of them extremely 

 minute, much smaller than their relatives 

 in other waters, and scarcely larger than 

 the species of Eviota, among which they 

 live. These minute fishes are mostly red 

 in color, sometimes partly black. Again 

 one species {Enneapterygius atriceps) is 

 found in the Hawaiian reefs, and again 

 six species (E. minutus, E. hemimelas, E. 

 htulsoni, E. tusitalm, E. cerasinus and E. 

 tutuilce) live together in the coral heads of 

 Samoa. 



The more usual distribution of a group 

 of closely related fishes may be shown by 

 the group of silver-fin minnows, the section 

 Erogala, in the genus Notropis among the 

 fishes. 



All these are small minnows, with large 

 scales, and with the dorsal fin marked by ai 

 large black blotch on its last rays above. 

 This fin in the males is tipped with a broad 

 stripe of silvery or milk-white pigment, 

 and sometimes also shaded with bright 

 red, orange or blue, very conspicuous in 

 the breeding season. 



The simplest, most primitive and most 

 widely distributed form is Notropis whip- 

 plii of the Mississippi Valley. Near to 

 this in the Upper Tennessee is Notropis 

 galacturus. In the Ozark range is Notropis 

 camurus. Farther south a black spot ap- 

 pears at the base of the tail. This marks 

 Notropis oiotatvs in the Rio Colorado of 

 Texas, Notropis venustus in the Rio 



Sabinal, Notropis cercostigma in Pearl 

 River, and Notropis stigmaturus in the 

 Alabama. On the eastern part of its 

 range, the nearest relative of Notropis 

 ivhipplii is Notropis analostanus of the 

 Potomac. Near to this is Notropis niveus 

 of the North Carolina rivers and No- 

 tropis cJiloristius of the Santee. Other 

 variants from these are Notropis eip-y- 

 stomus of the Chattahoochee, Notropis 

 xcenurus of the AUamaha, Notropis cceru- 

 leus, callistius and trichroistius of the 

 Alabama and Black Warrior, the last two 

 Avith scarlet on the dorsal. Finally come 

 the most specialized extremes, Notropis 

 pyrrhomelas of the Santee and Notropis 

 hypselopterus of the Mobile. Each south- 

 ern river has one or more species of this 

 type, and the streams of Georgia have been 

 invaded from the north and from the west, 

 the two types meeting in the basin of the 

 Alabama. 



In the little group of minnows called 

 Hydrophlox, another section of the genus, 

 Notropis ruhricroceus, and its allied species, 

 scarlet, black and golden, are distributed 

 in precisely the same fashion, and about 

 the same number of species are developed. 

 Those found in the Mississippi River have 

 the widest range of distribution and the 

 least specialization in their traits. Those 

 in the clear waters of the southern slope 

 of the Blue Ridge are most intensely 

 colored, most specialized in the traits, and 

 show the narrowest range in distribution. 



If fishes were as easily preserved, meas- 

 ured and examined as birds, and if they 

 were studied by as many keen eyes, we 

 might find perhaps that each of these spe- 

 cies is again broken up into races or sub- 

 species, their traits determined in some 

 degree by their individual parentage, in 

 larger part by the local selection they have 

 undergone in their diverse waters and sur- 

 roundings. This is certainly probable in 



