70 CATALOG OF FOSSIL FISHES IN THE MUSEUM 



ventrolateral (F), with some fragments apparently of 

 other ventral plates, and, behind these, a part of the 

 notochordal area (N) delimited by neural (n.a.) and 

 haemal (h.a.) arches. 



The dorsomedian is shown in outer view. Its anterior 

 margin, and the front portion of the right side are gone, 

 but the left side shows the anterior emargination, so 

 characteristic of this species (see figure of type, PI. 15, 

 fig. 2), and at once enables us to identify the form as 

 S. ringuehergi. The posterior process of the plate is also 

 preserved. 



The postero-ventrolateral present is that of the right 

 side, shown in outer view. It is very thin, thinner pro- 

 portionally than in a Dinichthys of the same size, and 

 where the bone has weathered away, the impression in the 

 matrix shows rings of growth. 



The notochord — or more properly, the space occupied in 

 life by the notochord — is preserved for a length of 29 cm. 

 It measures 40 mm. in diameter near the anterior end of 

 the preserved portion, and does not, in this portion, at 

 any rate, decrease much in diameter; at the posterior end 

 of the preserved portion it is 35 mm. in diameter. The 

 neural and haemal spines (arches?) are not sharply pre- 

 served, although it is seen at a glance that one set, evi- 

 dently the neural spines, are higher than those of the 

 opposite side, the haemals. This notochordal region 

 resembles that frequently found in specimens of Coccos- 

 feus from the Old Red Sandstone, except, of course, that it 

 is broader, as it should be in an animal much larger than 

 Coccosteus. 



The only other example of the notochord in a dinich- 

 thyid, is one collected years ago in the Cleveland shale 

 of Ohio, and preserved in the American Museum in New 

 York. This, also, apparently belongs in the genus 

 Sfenognathus.^° 



Horizon and locality. — Rhinestreet Shale; Eighteen 

 Mile Creek near Hamburg, N. Y. Collected by W. L. 

 Bryant, 191 6. 



'"No. 2454 Amer. Mus. Trans. N. 7. Acad. Sci.. xv. 157, pi. vii, iS 



