108 | 
It will be seen that, excepting the gradual increase of the num- 
ber of fishes eaten, these data show’ no especial difference in the 
young of different ages. Smaller specimens and a larger number 
from a greater variety of situations, would be necessary to exhibit 
this difference. | 
The food of the young as a whole, apparently, does not differ 
essentially from that of the large-mouthed species, except in the 
probably greater importance of ‘the insect element,—especially 
Corixas, which in these twenty-four specimens amounted to fifty per 
cent. of the food—and the inferior importance of fishes. 
This peculiarity is expressed in a slightly different manner, in the 
food of the adult. The three specimens examined had eaten only 
fishes (Noturus flavus and Percina caprodes) and crawfishes (Cambarus 
propingwus),—thirty-eight per cent. of the former and sixty-two per 
cent. of the latter. | 
This is the first of several instances in which the ratio of fishes 
in the food of allied species and genera was found to correspond to 
the size of the mouth, being largest in those with the largest oral 
opening.* 
TABLE OF THE Foop oF MIcROPTERUS. 
M. PALLIDUS. M. SALMOIDES. 
allio | By Bb Apo eee 
5 5 Z > a. = B= =z 
ae eam ee fan | cen eat | 
ie Boh ie aes Pees Aree hae 
3 oad eee pea, : ae heron ue 
et eae MR eH | po NE ie 
oS ° @ 2 : © oO S 
5 Sn hon 4 Sa Neer Ri 
<a = = = ‘ 4 = i 
5 fo) 5 =) : ) Sy al ete 
: : CD ARS: urna) ee ge a hai 
et a ee ate era aes 
te ea are } tee ec ae 
. 1 a - . ° 
Number of specimens....... ys ce eee 5 6 2 4 4 7. 10) 7 
[ PISHHS. veloc ace seo eee | 20 kes we aan SOW ose | 05 14 
Acanthopteri nic. hoe eee oe ee eee Aad rt aed ha BE TSN aee 2 alee Sedans 
OGG ts Re eel fey ruins eden eee ae Seat Poke aerrc hes a1 AES DEES eee er - 
DOTY SOMA nceguve secs tite onde cea re, ec ec aes eee BSH owes aru siteeee. ae 3 
Cyprinids... 555k eee er ete’. | ee ee oe DGC ve. 1157 aa Raps Ss 
“ eCampostomat..s ae EN a ee Ameer eds oc. J eb kemaes | Tis BEE. Tee tats ipa We Yi ny 
Bdlaridcei.: oy coe eee oe ree ee eT he aan +2 O7 ihvas ac epdeamued Galen cen 
Noturis Mavis sen tac aces oan eee. cl pcan aoe eee fail tn eee Lian te cee 
LISSENGROTHS Ac Pbr ee eee eee eS 46) 100}, 100}. ti 95 89, 07) ..228 
Undetermined. larves.(22 12x, Ce ee. BO rei viemee \eeeen ee Sengees gaeeee eee Y 
Le Diptera: larven).ic. fis gacedays tects 0212 = ceheneee a semen Hg 4h 05s ea ee P 
Culidideae: usar Fer an a ee, Rinse Fa el Rea Hee ee O22 eee ef 
# Chironotaus es 209.52 Seo ee 08) calee | 2 Ee cal eae ed eae [isos eal 4 
Mus@IdR feo. 6 ec ec ee ees re eb ee Fn ee es ee 
2. Coleoptera (larve)}...... Pee Pe 2k Ra Menem Wek yn eR 4 eae OB ecuoes 
Dytiscidis 2o ei oe Se. sn Ve Danae fale OF) che. 
By drophitidaa fy .co oe es gcc ae teen. es | Soe ele eee | ee ee Ty) aah) 
ee | 
*The frequency with which these two species of black bass are confounded makes it 
desirable that a single reliable character should be selected by which they can be in- 
variably distinguished, whatever the age of the specimen, This character is afforded by 
the size of the scales, the small-mouthed species having the smaller scales. In this 
species there are eleven longitudinal rows of scales between the dorsal fin and the row 
of perforated scales running along the middle of the side, called the lateral line. In the 
large-mouthed species, there are never more than nine suchrows. The young are easily 
distinguished by the longitudinal black stripe along the side of the largé-mouthed bass, 
which is wanting in the young of the other species, ; | 
