PLATE XXXI. 



PAGK 



Fig. 87. MYTILUS QUADRATUS. Natural size. 191 



Fig. 88. MODIOLA MAJOR. A rather small specimen. 191 



Fig 89. MKLKAGRINA AUTJQUA. Natural size. 192 



Fig 90. INOCEKAMUS ELLIOTII. A cast. 193 



90 a. Form of the ribs from the impressions in the matrix. 



