452 EXPLANATION OF PLATES. 
FIGURE, PAGE. 
59, 60. Syntrielasma hemiplicata, Halil. Carb.; Ills., . 382 
oa 62. Productus giganteus,Sowb. 1. Carb. Limest.: Eng., 332 
63-65. Productus horridus, J. Sow b. Zechstein, Gera, . 332 
66. Strophaiosia excavata, Geinitz. Paleozoic; Europe, 333 
67, 68. Strophalosia (Aulosteges) ee de Vern: 
Permian; Russia, ‘ . 333 
69-71. Chonetes striatella, Dalm. LO ‘Silur.; Europe, : aa3 
72-15. Crania anomala, Miiller. ¢; Zetland. 72, ventral 
valve; 73, dorsal valve; 74, ditto, with animal, the 
mantle removed; a, anterior adductors; a’, posterior 
adductors; c¢, posterior adjusters; ce’, cardinal 
muscle; r, 0, central and external adjusters, . . 339 
76, 77. Crania (Craniscus) velata, Quenst. U. Jurassic; 
Oerlingerthal, . ; : : . 330 
78-80. Crania (Ancistrocrania) Parisiensis, Defr. Upper 
Cretaceous; France, . 2 : é : E . 335 
81, 82. Monomerella prisca, Billings. U. Silur.; Ontario, 
Canada, ; ! : ; E f ; : . 836 
PLATE 140. 
83, 84. Dinobolus Conradi, Hall. ee Limestone ; 
Leclaire, Iowa, . ' : : . 336 
85=87. Trimerella Lindstromi, Dalm. U. Silur.; Gotland, 336 
88-93. Discina (Dicinisca) lamellosa, Brod. Recent; Peru. 
91, dorsal valve ; 92, ventral lobe; 93, the animal as 
seen on the removal of part of the lower mantle-lobe ; 
the extremities of the labial arms are displaced for- 
wards, in order to show their spiral terminations; Pp 
is the expanded surface of the pedicle; the mouth i is 
concealed by the overhanging cirri. The mantle- 
fringe is not represented. ww, umbo ; : /;, LOVAINEN 340, 
disk ; 4 a, anterior adductors ; a’ 5 posterior adductors: 
ec, ce’, central and posterior adjusters; 7, external 
adjusters, . : ‘ : : 5 : 5 - 338 
94, 95, Obolus Davidsoni, Salter. Wenlock Limestone ; 
Dudley, é ; : : : : : : . 338 
96-98. Trematis terminalis, Emmons. Silur.; Europe, 
N. America, ‘ ‘ : : . 340 
59; nye Obolella chromatica, Billings. T.. Silur. ; Canada, 33 
.. 2. Kutorgina cingulata, Billings. Silur.; Canada, . 339 
3. 4, Leptobolus lepis, Hall. Hudson River Gr.; Cincin- 
nati, Ohio, . : ; : : : : . 339 
5. Schizocrania filosa, Hall. L. Silur.; Ohio, . : . 340 
6-8. Siphonotreta verrucosa, Verneuil. Silur.; Europe, . 340 
#.10 Acrotreta subeconica, Kutorga. Silur.; Europe, . 341 
