538 C. R. EASTMAN 



neither of which, however, exhibits the caudal region satisfac- 

 torily, nor are the heads well preserved. Only the dorsal and 

 anal fin-spines are displayed by the larger specimen ; but in the 

 smaller all the fin-spines are preserved, although the dorsal is 

 slightly displaced and the distal ends of the pectorals are want- 

 ing. The accompanying 



figure, based on both speci- 

 mens, is of composite na- 

 ture, and represents the 

 general outline and propor- 

 tions of the fins, the re- 

 F1G.-3. Calacanifms exiguus, s P . nov. st0 red parts being indi- 



Coal-measures, Mazon Creek, 111. Complete 



individual, lacking posterior dorsal and anal cated in dotted lines. 



fins. Xf. 



GENUS CCELACANTHUS, AGASSIZ. 



J. S. Newberry records having received from Mazon Creek 

 "a single specimen each of Enrylepis and Coelacanthas, probably 

 not distinct from those found at Linton, Ohio." No examples 

 of the former genus have come under the writer's observation, 

 but ornamented scales and head-plates referable to Ccelacantlms 

 sometimes occur in Mazon Creek nodules, and very rarely there 

 are found complete fishes of small size, evidently quite distinct 

 from other described species. In most specimens the posterior 

 dorsal, anal, and pectoral fins are lacking, and it seemed at first 

 sight as if the second dorsal had become lost through specializa- 

 tion. One individual, however, shows it very distinctly, and the 

 absence of this and the anal in the remaining examples is to be 

 attributed to faulty preservation. 



Ccelacanthus exiguus, sp. nov. 



Description. — A small species, attaining a maximum length of about 

 4.5'™. Trunk narrow and elongated, the head occupying about one-fourth of 

 the total length. First dorsal consisting of relatively few stout ravs, and sit- 

 uated slightly in advance of the pelvic pair ; second dorsal midway between 

 the first dorsal and principal caudal ; the latter comprising nine stout rays 

 above and below. [Scale-structure and ornamentation of head-bones not 

 observed.] 



