Pig-. 
Pig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Fig. 
Figs. 
Fig. 
Fig. 
Fig. 
PLATE I—Continued. 
Lingula quadrata (Eichwalcl), Hall. 
13. A large example, from which much of the shell has been exfoliated ; showing the median septum, 
which is frequently more strongly developed, and the projection of the umbOSal region of the 
pedicle-valve beyond the apex of the brachial. The prominence of the ;iatter feature is to some 
degree due to the displacement of the valves. 
Trenton limestone. Trentbh 'Falls, N. Y. 
Lingula Iowensis, Owen. 
14. The interior of a brachial valve, probably, refer able to this species; showing the conspicuously 
developed median septum, the well-defined central scars (h), and the progressive laterals (x). 
Natural size. 
Galena limestone. Fountain, Minnesota. 
Lingula spatulata, Vanuxein. 
15. A pedicle-valve (?), retaining the shell, and showing evidence of a median septum in the umbonal 
region. X 6. 
Genesee slate. L Canandaigua Lake, N. Y. 
Lingula compta, sp. nov. 
16. A specimen of the brachial valve (?) ; showing the lateral impressions and the median septum ex¬ 
tending to the anterior margin. X 2. 
Hamilton shales. Canandaigua Lake, N. Y. 
Lingula complanata, Williams. 
17. The interior of a brachial valve; showing the fulcra of the lateral muscles. X 2. 
Portage group. Ithaca, N. Y. 
Lingula sp ? cf. Cuyahoga, Hall. 
18. A pedicle-valve, retaining a portion of the shell-substance, and showing the position of the lateral 
scars. X 2. 
Chemung group. Panama, N. Y. 
Lingula anatina, Lamarck. 
19. The interior of the pedicle-valve ; showing the character of the muscular scars and septa as they 
appear when the muscular bands and the mantle are wholly removed. Natural size. 
20. Brachial valve of. the same. Natural size. 
Recent. Philippine Islands. 
Lingula Elderi, Whitfield. 
21. 22. Copies of the lithographic figures given by Mr. Whitfield (Geol. Surv. Wisconsin, vol. iv, pi. 27, 
figs. 4, 5), of the interiors of the pedicle and brachial valves, respectively. Drawn from a cast 
which preserves the internal characters with remarkable completeness. X 2. 
Trenton limestone. Near Rochester, Minnesota. 
Lingula cf. densa, Hall. 
23. The interior of a pedicle-valve ; showing the septum and lateral scars. X 2. 
Hamilton shales. Centerfield, N. Y. 
DIGNOMIA, Hall. 
Page 11. 
Dignomia alveata, Hall. 
24. A cast of a brachial valve; showing the long, sharp median septum and the fainter diverging 
lateral septa. Natural size, 
Hamilton shales. Fultonham, N. Y. 
25. A portion of the interior of a large pedicle-valve (?), with a shorter and broader median septum, 
and distinct lateral septa. Natural size. 
Hamilton shales. Canandaigua Lake,' N. Y. 
