420 Davis — On the Fossil Fish of the Cretaceous Formations of Scandinavia. 



The articulated rays diminish in length posteriorly, and are divided by repeated 

 bifurcations similar to those of the dorsal fin. The caudal fin is not well 

 preserved in any of the specimens ; the one figured on Plate xliii. is the best. 

 The lower lobe consists, apparently, of eight or nine strong articulated dichotomiz- 

 ing rays, connected with the vertebral column by a hypural bone, but their length 

 cannot be determined ; the upper lobe of the tail appears to have had a similar 

 number of rays. The body of the fish is split down the middle, and consequently 

 the pectoral fins are not exhibited, but their position may be indicated by a 

 number of ridges showing through the scales almost midway between the dorsal 

 and ventral surfaces. The ventral fin is supj)orted from the scapular arch by a 

 largely-expanded pubic bone. It is situated on the ventral surface, immediately 

 under the posterior margin of the gill-cover. The anterior ray is spinous, with a 

 length of 0'02o m., it is thick, and sharply-pointed. The number of fin-rays 

 cannot be determined, but the fins were of large size. 



The scales are of medium size, the height of those situated behind the gill- 

 covers being 0'00-im. The posterior margin is circular, and slightly imbricated. 

 The surface is ornamented with striations, running more or less parallel with the 

 axis of the body. The direction of the lateral line {lat.) is indicated by series of 

 foramina, which occur on alternate scales along the su|)erior portion of the body. 



This species is readily distinguished from any previously described by the 

 number and position of the spinous rays of the dorsal fin, the number of vertebrae, 

 together with the size of the scales. The scales of Hoplopteryx sipjtei, Agassiz, 

 are not known; those of H. syriacus, P. & H., and H. oMonc/iis, Davis, from the 

 chalk of Mount Lebanon, are much larger than those of the Swedish fish ; the 

 scales of JI. superbus, Dixon, are also large. In If. si/riacus there are six spinous 

 rays in the dorsal fin, and its anterior ray is inserted, after a considerable interval, 

 behind the head. H. sippci, Ag., has five spinous rays, which are inserted 

 immediately behind the occiput; the number of vertebrae is about two-thirds 

 that of the species now described. II. oblongus is possessed of six or seven dorsal 

 rays, and its vertebral column consists of thirty-two vertebrae. 



Formation and Locality — Etage Danien (zone with Anancites sulcatus, Goldf.) : 

 Saltholm Limestone ; Limhamn, Scania. 



F.v coll. — Geological Museum, Lund University. 



Ilopilopteryx, sp. 



(PI. XLii., figs. 19, 20.) 



A number of detached scales occur in the Lund Museum from the chalk of 

 Limhamn. They have a transverse diameter of 0-025 m., and the length, antero- 



