136 



NEW YORK STATE MUSEUM 



The distinctive features of Scaumenacia may be summarized as 

 follows : 



Body-form gracefully fusiform, about as much compressed as 

 Neoceratodus. Maximum depth equal to head, and contained six 

 times in total length (including caudal). Fins well developed ; paired 

 fins archipterygia, large and relatively slender, with scaled central 

 portion and divergent marginal dermal rays. Length of pectoral one 

 and one-third tires the maximum depth of body; when adpressed 

 to body extending over two-thirds the distance from origin 

 of pectoral to origin of ventral. Ventral longer and somewhat 

 broader than pectoral, about one and one-half times the maximum 

 depth of body ; commencing slightly back of origin of second dorsal. 

 First dorsal very low, its maximum height one-seventh or one-eighth 

 its length ; commencing considerably back of occiput, but somewhat 

 nearer to origin of pectoral than that of ventral. Space between 

 dorsals one-seventh the length of first dorsal. Second dorsal very 

 much higher than first, its maximum height two-thirds the maximum 

 depth of fish. Caudal strongly heterocercal. Anal relatively small, 

 situated close to lower lobe of caudal. Lateral line present. 



Cranium. Three specimens (2875 Yale Museum; 7656 and 7677 

 American IMuseum) in the materials in hand, show the cranium in 

 fair preservation. Figure 4 is based on these, more especially on 

 p ^^ the Yale specimen. The ar- 



^- -^cj rangement of the cranial ele- 



ments is quite like that in 

 Phaneropleuron as figured by 

 Goodrich [3, p. 239]. There is 

 a median supra-temporal (MS), 

 preceded by a pair of parietals 

 (Pa), and anterior to these a 

 pair of frontals (Fr). The 

 suture between the frontals is 

 rather vague in the Yale speci- 

 men, but it is very clearly shown 

 in an American Museum speci- 

 men (7677). There are also a 

 number of other paired plates 

 arranged symmetrically on 

 either side — pterotics (Pter), 

 supraorbitals (Su. O), and 

 several others whose homology is not quite clear. The rostral region 

 is lacking in all the specimens in hand and is indicated in the figure 

 by analogy with other dipterine crania. 



Pter 



MS 



Fig. 4 Head of Scaumenacia curta 

 (Whiteaves). Fr, frontal; MS, median occipital; 

 Mx, maxilla; Op, oparculum; Pa, parictil; 

 P. mx, premaxllla; PiSr, pt3rot':c; Su. O, supra- 

 orbitils. 



