Explanation of Plates. 

 PLATE I. 



LiNGULA COMPTA, Hall. 



Page 325. 



Fig. 1. A specimen of the brachial valve (?) ; showing the lateral impressions 

 and the median septum extending to the anterior margins, x 2. 

 Hamilton shales. Canandaigua Lake, N. Y. 



LiNGULA LINGULATA, Hall. 



Page 327. 



Fig. 2. The pedicle-valve, from which the epidermal layer is partially exfoli- 

 ated; showing the peculiar deflection of the anterior margin, which is a 

 constant feature. X 2. * 

 Clinton group. Near Hamilton, Ontario. 



LiNGULA SCUTELLA, Hall. 



Page 326. 



Fig. 3. An internal cast, indicating that the muscular region of the valve was 

 depressed instead of thickened and elevated, as is usually the case. X 2. 

 Chemung group. Allegany county, N. Y. 



LiNGULA T^NIOLA, Hall. 



Page 327. 



Fig. 4. The pedicle- valve ; showing the peculiar surface ornament, crossed 

 near the beak by concentric growth-lines. X 1 .5. 

 Clinton group. Clinton, N. Y. . 



LiNGULA (Glossina) flabellula, Hall. 



Page 326. " • 



Fig. 5. A very large example from which a portion of the shell has been 

 exfoliated, without showing any traces of muscular markings. 

 Waverly group. Sciotoville, Ohio. 



Fig. 6. A similar valve, exposing the inner laminae of the shell, with faint' 

 radiating lines . 

 Bereagrit. Berea, Ohio. 



LiNGULOPS Granti, Hall. 



Page 328. 

 Fig . 7 . The interior of a brachial valve . x 6 . 



Fig . 8 . The interior of a pedicle-valve . The muscular area is here developed 

 into a well-defined platform, while in the species L. Whitfieldi and L . 

 Norwoo^i, it retains its linguloid character . x 6 . 

 Niagara group. Hamilton, Ontario. 



374 



