THE 



GEOLOGICAL MAGAZINE 



NEW SERIES. DECADE V. VOL. X. 



No. XII.— DECEMBER, 1913. 



OE-IG-ITsT-A-IL. .A.IiTZOLE!S. 



I. — Oif A New Specimen of the CREXACEorrs Fish Portheus ■ 

 31 OL OSS us, Cope. 



By Arthuk Smith Woodward, LL.D., F.E.S. 



(PLATE XVIII.) 



SEVERAL nearly complete skeletons of tlie primitive teleostean 

 fish Fortheus molossus are now known from the Chalk of 

 Kansas '■ ; but none is better preserved than a remarkable trunk, 

 nearly 12 feet in total length, lately obtained for the British Museum 

 by Mr. Charles H. Sternberg. The specimen is shown, of about 

 2-4 of the natural size, in the accompanying Plate XVIII, where it is 

 seen mounted with the head of another fish of the same proportions. 

 All the bones remain embedded in the matrix exactlj'' as they were 

 found, and there is no restoration beyond slight repairs. 



The vertebral centra in the fossil form a continuous undisturbed 

 chain from the pectoral arch backwards, only damaged a little by 

 crushing. The total number of dorsal vertebrae is abput fifty-five, 

 while that of the caudals is thirty-three. From the pectoral arch 

 backwards to the caudal fin all the centra are impressed on the 

 side by two deep longitudinal depressions, of which the upper is the 

 larger. In a few of the anterior centra the lower lateral depression 

 is especially small, and restricted to the hinder half. The lower face 

 (well seen in some of the distorted anterior centra) is flattened 

 between the two longitudinally extended pits in which the bases 

 of the haemal arches are fixed. The gently arched ribs are long and 

 slender, all reaching the ventral border of the fish. Each rib is 

 impressed by a slight longitudinal groove, and its upper end is 

 somewhat expanded where it fits loosely in the socket of a small 

 parapophysis. This parapophysis, which does not appear to be 

 firmly fixed in the pit of the centrum, is much more expanded in 

 front of the socket than behind, and is in direct contact with the 

 adjacent pai-apophyses. The arrangement is well shown in a drawing 

 by 0. P. Hay,^ in which it was originally mistaken for a neural arch. 

 In the anterior half of the abdominal region in the fossil the neural 

 arches are accidentally removed, but further back several are in place, 



■^ A. B. Crook, Palcsontographica, vol. xxxix, p. 109, fig. 1, 1892 ; H. F. 

 Osborn, Bull. Amer. Mus. Nat. Hist., vol. xx, pp. 377-81, pi. x, 1904; 

 C. E. McClung, Kansas Univ. Science Bull., vol. iv, p. 243, pi. xii, 1908. 



2 0. P. Hay, Zool. Bull., vol. ii, p. 47, fig. 12, 1898 ; corrected in Bull. 

 Amer. Mus. Nat. Hist., vol. xix, p. 56, 1908. 



decade v. — ^VOL. X. — NO. XH. 34 



