PLATE XVI a. 

 Dalmanites (Cuypii.kus) COMIS. 



Page 41. 

 Fig. 1. The internal easi of a pygidium, enlarged to three diameters, and considerably restored. 

 Upper Helderberg limestone. Cayuga, Province of Ontario. 



Dalmanites - (Cryph^eus) Pleion e. 



Page 41. 

 Kif, r . 2. View of the type specimen. 



Corniferous limestone. Falls of the Ohio. 



Dalmanites (Cryph.eus) Boothi. 

 See Plate 16. 

 Fig. 3. A small pygidium, showing the flattened marginal spines. 



Hamilton group. Darien, Genesee county. 

 Fig. 4. A larger pygidium, in which the marginal spines are longer and gently rounded, and the terminal 

 spine acute. 



Hamilton group. Canandaigua Lake. 

 Fig. 5. The internal surface of a pygidium. in which the spines are broad and flat. 



Hamilton group. Near Geneseo, Livingston county. 

 Fig. 6. Similar view of a smaller pygidium. with more elongate spines. 

 Hamilton group. Near Geneseo, Livingston county. 

 Fig. 7. A large pygidium, with spines of the normal character. 



Hamilton group. Canandaigua Lake. 

 Fijf • 8. Three of the marginal spines of the specimen represented on plate 1 6, fig, 1, enlarged to three 

 diameters. 



Dalmanites (Ckyph.eus) Boothi, vjir. Calliteles. 



See Plate 16. 

 Fig. 9. An imperfect pygidium, referred with some hesitancy to this variety. The long, acute spines are 

 different from those in the normal adult forms of either the species or the variety. No cephala 

 accompanying such pygidia in the Hamilton shales have been observed. 

 Hamilton group. Jay cox's Run, Livingston county. 

 Fig. 10. A pygidium with similar characters. The associated cephala bear the diagnostic characters of 

 this variety. 



Tully limestone. Goodwin's, Cayuga Lake. 

 Fig. 11. A normal adult pygidium, enlarged to two diameters, showing the elevated, lanceolate marginal 

 spines. 



Hamilton group. Canandaigua, Ontario county. 

 Fig. 12. The pygidium of the youngest individual observed (plate 16. tig. 5). enlarged to twelve diameters, 

 showing the incurvature of the axis ; the long, terete marginal spines, diminishing in length 

 posteriorly, and the undeveloped terminal spine. 



Hamilton group. Canandaigua, Ontario county. 

 Fig. 13. An individual in a slightly advanced stage of growth (plate 16, tig. 6), enlarged to ten diameters, 

 showing an approximation in the relative length of the spines. 

 Hamilton group. Canandaigua, Ontario county. 

 Fig. 14. An individual in a later stage of growth (plate 16, tig. 7), enlarged to nine diameters, showing the 

 approximately equal length of the spines, except in the last pair, and the increasing size of the 

 terminal spine. 



