CORRIGENDA. 
Plate 1, fig. 8. Some of the short spines at the summit of the proboscis are erroneously merged 
into the branches of the arms, making the latter appear as if continuations from the spines. 
Plate 4. The references of figs. 10 and 11 should be reversed. 
Plate 12, figs. 9, 10, 11 & 12. Orthis quadrans, referred to in text as O. subcarinata. A study of 
the interior structure of the valves has shown these forms to be quite distinct from 0. subcarinata, 
and a well-marked species. 
Plate G8, p. 341. Bucania profunda (B. profunda , n. s., by mistake) should be cited Euomphalus 
profundus, Vanuxkm, Gcol. Report Third District New-York, p. 117, f. 2. 
Plate 72 a. Erroneously referred to in the text, pages 347 and 348, as Pl. 02 a. The correction on 
explanations of plates does not correct the reference. 
Plate 73, fig. 24 a, is an enlargement of a portion of the eye of P. hudsonicus. 
Plates 79 a and 79 b, containing figures of Lcp&rditia and Bcyrichia, are omitted from this 
volume but will be given in a future one. 
Plate 95 a. The reference f, after Strophodonta magnifica, should be after Orthis cuviberlandiaf 
t This species may be compared with Orthis hipparionyx. 
Plate 106. Explanations of figures omitted : 
Fig. 3. Rhynchonella rnultistriata, p.440. 
Fig. 4. Rhynchonella principalis, p.443. 
Plate 92, and page 40G, change the name Piscina grandis to Piscina ampla, n.s.; the former 
name being preoccupied. 
# # * In the text of the Introduction, page 8, in the righthand column of names of rocks, the Galena 
limestone is by mistake placed below the Trenton limestone, when it should be placed above. 
