74 CONNECTICUT GEOL. AND NAT. HIST. SURVEY. [Bull. 



This gracefully formed and elaborately ornamented species is 

 known by a dozen or more examples, all derived from a single 

 locality near Durham, Connecticut. Among these are several 

 excellently preserved individuals, including the type shown in 

 Plate VII, material which might be expected under ordinary cir- 

 cumstances to yield valuable enlightenment concerning cranial 

 structure. Progress in this direction, however, is subject to the 

 limitations imposed by the peculiar nature of the head bones 

 themselves: that is to say, by the highly sculptured and heavily 

 enameled outer surface which completely conceals suture lines. 

 It is nevertheless permissible to draw certain inferences con- 

 cerning the extent and arrangement of plates forming the cranial 

 roof by noting the centers of radiation and territory traversed 

 by the superficial radiating rugae; and the general pattern thus 

 revealed has been found to agree with typical Eugnathidse. The 

 dorsal aspect of the cranial roof, together with some of the 

 facial bones and opercula, is favorably exposed for study in the 

 specimen represented in Plate VIII, the original being preserved 

 in the Yale Museum (Cat. No. 2608). The lateral aspect is even 

 more favorably shown in the original of Plate VII, which is the 

 property of Wesleyan University Museum (Cat. No. 907). 

 This example, though of a young individual, is admirable for its 

 presentation of fin and scale structure, and for showing the 

 normal body contour. 



In connection with the distribution of this form, it should be 

 recalled that its accompaniment by Semionotus, Catopterus and 

 a Crossopterygian genus (Diplurus) is a fact of capital im- 

 portance in assigning the fauna in question to a horizon equivalent 

 to the Upper Muschelkalk and Lower Keuper of the European 

 marine Trias. All the evidence derived from a study of the 

 fossil fishes is in favor of establishing a correlation at a level 

 embracing these two horizons, but probably not extending higher 

 than the basal division of the Keuper in the Mediterranean 

 region. "^ For a recent review of the evidence for establishing an 



^ That is, the Newark fauna cannot be regarded as younger than the faunas of 

 Besano, Lombardy, and of Raibl, Carinthia (Lower Alpine Keuper), which mark the 

 uppermost range of one of the intercommunal genera Ptycholepis. The Upper Muschel- 

 kalk (Ladinian) terms of comparison are furnished by two Semionotid genera, one 

 Captopterid, and one Crossopterygian, according to the revised determinations of 

 Professor G. De-Alessandri (1910). 



