68 



THE COAL MEASURES AMPHIBIA OF NORTH AMERICA. 



wix^ 



The reference by Cope of this genus to the Caudata is one of the most interesting 

 facts connected with the Paleozoic Amphibia. He says: "The present genus is, 

 then, to be referred to the neighborhood of Amphiiima and Protonopsis, but forming 

 the type of another family" (123). He regards the branchial apparatus as being 

 more fish-like than that of any of the modem genera. It is possible that Cocytimis 

 gyrinoides was a larval branchiate and consequently aquatic form. It should be 

 more fully compared with Erierpeton hranchialis from the Mazon Creek shales 

 when better known, as well as with Ilyphasma Icnis from the Linton locality. 



All three of these forms are included, provisionally, under the Cocytinidae. 



Cocytinus gyrinoides Cope. 



Cope, Proc. Am. Phil. Soc., xii, p. 177, 1871. 



Cope, Trans. Am. Phil. Soc., p. 278, 1874. 



Cope, Geol. Surv. Ohio, 11, pt. 11, pp. 364-365, pi. xxxix, fig. 4, 1875. 



Type: Specimen No. 8613 G, American Museum of Natural History. 



Horizon and locality: Linton, Ohio, Coal Measures. 



Two specimens of this interesting amphibian are known, one of them fairly com- 

 plete (No. 2564, Am. Mus. Nat. Hist.). The type specimen p^* 



consists of the inferior bones of the cranium in a fairly complete 

 state of preservation, with the muzzle and its teeth; also 8 

 anterior vertebrae, with their short recurved ribs. 



The condition of the hyal elements in the type specimen is 

 as follows: the haemal elements of the first branchial arch are 

 partially concealed on both sides of the ceratohyal. An expanded 

 truncate face for attachment to the axial element is visible on 

 both sides, but the body of the bone is flat and presents the 

 edge of the specimen. 



The first pleural element proceeds from just behind the axial- 

 hyal; it is longer than the other pleural elements. A slender 

 bone is visible extending from the space between the cerato- 

 hyal and mandibular angle; it may, therefore, pertain to the sus- 

 pensorium of the jaw as well as to that of the hyiod arch, or 

 be squamosal as well as stylohyal. The second hremal bone is 

 slender, but with an enlarged axial extremity; that of the right 

 side is not so well preserved as to be safely determined. The 

 third haemal elements are the smallest, and originate imme- 

 diately in front of the occipital condyles and diverge outwards 

 and backwards. They are little curved, subcylindric, and slightly 

 expanded at the extremities. 



Of the pleural elements the first and second are little curved and the first is 

 marked by a pit or foramen on the under side near the distal end, which is clearly 

 visible on both sides of the specimen. The third and fourth pleurals are more curved 

 and the outer ends slightly expanded and directed backwards. 



The obverse of the specimen (fig. 16) shows that the anterior axialhyal is wedge- 

 shaped. The lateral basihyals are massive. The second haemal branchihyal is 



Fig. 16. — Obverse of Cocy- 

 tinus gyrinoides Cope, 

 from the Coal Meas- 

 ures of Ohio X 2. 

 pntx, prcmaxillcE; mx, 

 maxilla; m, mandible; 

 ah, axialhyal; h, basal 

 branchihyal ; ch, cer- 

 atohyal; bv, haemal 

 branchihyal; ft, bll, 

 bin, hi II I. pleural 

 branchihyals. 



