Literary Notices. XXVii 
the symmetrical teleosts the right and left optic nerves are dorsal in an 
approximately equal number of cases. He now extends the observa- 
tions to the flat-fishes and finds that the two families into which the 
sub-order Heterosomata is divided by recent systematists differ con- 
spicuously in this character. In the Soleidae the chiasmata are di- 
morphic, as in symmetrical teleosts; i. e., the right optic nerve is dor- 
sal in abeut half of the observed cases and ventral in about half. In 
the Pleuronectidae, on the other hand, the chiasmata are monomorphic 
for each species; in dextral species the left nerve is dorsal, in sinistral 
species the right nerve is dorsal. All species of this family that turn 
in only one direction have their dorsal nerves connected with their 
migrating eyes. In all species that have both dextral and sinistral in- 
dividuals, the dorsal nerve is connected with that eye which in the 
greatest number or in the nearest of kin migrates. The unmetamor- 
phosed young of the Pleuronectidae are not symmetrical in the same 
sense that symmetrical teleosts are, for they have monomorphic chias- 
mata. ‘The Soleidae are not degraded Pleuronectidae, but degenerate 
descendants of primitive flat-flshes, from which the Pleuronectidae 
have probably been derived. The monomorphic condition of the 
optic chiasma of the Pleuronectidae can be explained only on the as- 
sumption of natural selection. The flat-fishes afford striking examples 
of discontinuous variation. ae Fear” 
Brain Weights of Eminent Men.’ 
Dr. SpirzKa has tabulated 96 cases and made comparisons with 
the statistics of 800 brains of ordinary persons as given by BISCHOFF 
and MaRCHAND. ‘‘ The average (arithmetical) brain weight of the 96 
individuals is 1473 grams, exceeding the various averages given for the 
European brain by 75 to 125 grams, and this without allowing for the 
advanced age of this series; the average of 92 being 63 years.” ‘‘Itis 
further shown that the period of decrease [in brain weight] with age is 
deferred for fully a decade among the more intellectual persons, a 
point already alluded to by Dona.pson, and significant in connection 
with the longevity of healthy persons endowed with high intelligence.” 
The paper is accompanied by several instructive curves and tables. 
5 ee 
* Spitzka, Epwarp ANTHony. A Study of the Brain Weights of Men 
Notable in the Professions, Arts and Sciences. Philadelphia Medical Journal, 
May 2, 1903. : * ot th 
