PLATE TV II. 



Legend, pa. Posterior ailciucloi' scars. in, Meiliau imisciihir I'lilfruiii. 



aa. Anterior adductor scars. v. Vascular sinuses. 



b. Brachial nuiseular .scars. 



CRANIA, Eetzius. 



Page U5. 



CUANIA L.ELIA, Hall. 



Fig. 1. Four individuals attached to the pedicle-valve of i^li-ii>/<ir/iyiic/iii.s plan iiinhouiim. 

 Huilson River grouii. Oxford, Ohio. 



CUANIA AOARICINA, .sp. ilov. 



Fig. 2. An individual attached to a branch of Tkem.\toi"oua ; showing the characteristic sparse and 

 relatively coarse radiating ribs. X 3. 



Lower Helderberg group. Near Clarksrille. N. 1'. 



Crania tulciiella, sp. iiov. 



Fig. 3. An individual attached to the valve of Orthis sabcarinata. It difi'ei's from the preceding species 

 in its tiner, more numerous ribs and greater size. X 2. 



Lower Helderberg group. Near Clarksrille, N. V. 



Crania Boruexi, ILill mid Wliillicld. 



Fig. 4. An individual attached to a valve of Spirifer Owe/ii ; showing the very fine radiating striie, and 



the conformation of the upper valve to the surface of attachment. 

 Fig. 5. Protile of the same specimen. 



Hamilton limestone. Clarke county, Indiana 



Crania crenistri.vta, Iltill. 



Pig. 6. The interior of an upper valve ; showing the strong anterior adductor scai's and vei-y faint poste- 

 rior adductors. X 2. 



Hamilton hmestone. Falls of the Ohio. 

 Fig. 7. A portion of a cast of the internal surface in a decomposed cliert ; showing the filling of vertical 

 canals. X 25. 



Coi'uiferous limestone. Canandaiyiia, N. 1'. 

 Fig. 8. The interior of an upper valve ; showing the very strong antei'ior .addnclor scars with mar- 

 gins elevated, and the more obscure posterior scars. X 3. 



Hamilton limestone. Fall.': if the Ohio. 

 Fig. 9. The exterior of a large uppei- valve. Natural size. 



Hamilton group, ('anandaigna Lake, N. Y. 

 Fig. JO. A smaller uncompressed individual. 

 Fig. 11. Hi-ofile of the same. 



Hamilton grouj). Western New York. 

 Fig. 12. A valve of the .same, or a closely allied species, attached to Orthlt inqire.-(sa. X ;'i. 



Upper Devonian. Rockford, loioa. 



Crania Rowleyi, (tuiIcn . 

 Pig. 13. An individual showing the upper valve. X 2. 



Chotean limestone. Pike county, Missouri. 



Crania setigera, Hull. 



Fig. 14. An individual, referred to this sjiecies with some hesitation ; attached to a bi'anch of Monticdli- 

 PORA. It will be oliserved that for some distance about the anterior edges of the shell, where 

 the valve.s Ojiened for the admi.ssion of food-bearing watci-cni-reuts, the outward growth ot 

 the bryozoan cells ha* been obstructed. X 2. 



Trenton horizon Mianiapolis, Minnesota. 

 Pig. 15. An upper valve. X 2. 

 Pig. 16. Profile of the same. X 2. 



Ti'enton limestone. Mineral Point, Wisconsin. 



Crania .-^i'imgera, Hull. 



Fig. 17. The original specimen ; an individual attached to the shell of IViyiiehonelta Strirklandi. The 

 ornamentaliim consists of radiating rows of sharjily defined tubercles. X 3. 

 Niagara groui> Waldron, Indiana. 



