FRESH WATER MUSSEL SHELLS 139 
7. LEPTODEA (PARAPTERA) FRAGILIS. 
N 
Spec. Age L DVD DSD PD AD” PHE ARE il: 
4.44cm. 3.14cm. 1.44cm. 3. cm. |. Icm. 2. 2cm. |. 2cm. .9cm. 
3 
4.125% 114% 131% 125% 145% 118% -110% 128% 
5 220% 202% 218% 252% 201% 222% 170% 166% 
6 203% (195% 216%. 220% ..@18%., 222% 175% . 144% 
7 208% * 227% 230% - 233% 213% 216% 176% 177% 
8 201% %, 196%. -203.%-).215Y4 223% . 221%. 170%) 188% 
9, 191% .189% “148% 213%. 190% - 192% 157% - 155% 
12 290% 256% 262% 316% 309% 325% 250% 244% 
verage growth per year in each dimension for 12 years, 
61% 51% 59% 13% 67% 68% 42% 42% 
Depuctrions From TABLE oF PERCENTAGES AND REMARKS. 
Growth increase appears most rapid in PD, AD, and PHL; least 
in AHL, TH. Increase is at the same rate in L, DVD, DSD, while 
according to this data, growth is greatest at 12 years, increasing 
steadily up to this period. DVD, AD, PHL and TH apparently 
grow the most rapidly in the years 7-9, inclusive. PD, however, 
increases most rapidly years 4-6 inclusive. 
Two related species, Lampsilis gracilis and Lampsilis laevissima, 
have been observed by authors cited, (2). They found the first 
named of these species to increase 190% in length in one year. By 
my data, such a specimen would be between 11-12 years. The 
second is cited as one of the “‘paper shells,” increasing 14 to 2 in. 
per year, (12.7 to 50.80 mm.), in length. The latter represents in 
its lower ranges the amount of increase found among my shells. 
e 8. PROPTERA ALATA 
oO. 
Spec. Age L DVI aS PD IND Nall SNS | ADSL 
1 2 1.28cm. .85cm. .35cm. .85em. .33cm. .55cm. .45cm. .05cm 
1 a Me ZOOS AZO se ENF, AZ. 136% 78% 140% 
I Ds NOD, NOD 1059 105%. 136%. 118% 180% 90% 
I 6 257% 320% 328% 241% 379% 309% 363% 120% 
I 7 201% .247% 240% 202% 267% 245% 133% 100% 
I 8 371% 461% 554% 417% 369% 481% 255% 220% 
2 9 384% 473% 520% 423% 363% 473% 233% 240% 
2 10 511% 623% 780% 541% 560% 563% 493% 480% 
I 12.-703% °854% 1017% 764% 757% 927% 377% 100% 
I 13 668% 755% 871% 741% 681% 836% 365% 600% 
2 14 523% 600% 745% 568% 576% » 636% 300% 400% 
2 15 859% 854% 1128% 930% 1072% 1178% 471% 880% 
I 16 750% 820% 911% 823% 785% 909% 377% 500% 
| 20 812% 840% 1148% 930% 757% 1054% 400% 640% 
I 22 788% 794% 837% 811% 694% 863% 366% 480% 
Average growth per year in each dimension for 22 years, 
260% 294% 364% 282% 280% 324% 129% 190% 
