144 TRANSACTIONS OF THE AMERICAN PHILOSOPHICAL SOCIETY 



showing that apart from minor differences in the proportional development of certain parts 

 the two skulls exhibit the most arresting evidences of close relationship. He notes also 

 {op. ctt., Pt. VII, 1911, p. 253), that Ichthyodectes belongs among the distinctly synthetic 

 types of Cretaceous genera. "The skull of Ichthyodectes," he writes, "is mainly similar 

 to that of the surviving Chirocentrus, which belongs in the same or a closely related family; 

 but it differs in exhibiting a pit in the side of the otic region, which is now found, not in 

 the Chirocentridae, but in the Elopidse and Clupeidae." 



In Portheus the Ichthyodectes type becomes of gigantic size. The sharp upturning of 

 the mouth is due to a combination of a short snout with a depressed and anteriorly-placed 

 quadrate-articular joint. The circumorbital bones are large, the supramaxilla exceptionally 

 so. Mr. Sternberg's specimen indicates that the posttemporal was very large. The 

 posterior borders of the bones of the opercular region are not defined and the bones were 

 probably continued into a thin web. The chondrocranium of Portheus as described by 

 Hay (1903a) was fundamentally similar to that of the tarpon. 



Albulids. — The Albulidas (Fig. 37) are regarded by Woodward as "merely Elopine 

 fishes with a forwardly-inclined suspensorium, a small mouth and reduced branchiostegal 

 apparatus" (1901, p. vi). Ridewood (1904), after extended and intensive comparisons 

 of the skulls of Albula and the modern Elopidse, has shown that the two families agree in 

 possessing many primitive isospondyl characters but have few peculiar specializations in com- 

 mon. Albula itself dates back to the Lower Eocene and, according to Woodward (1901, p. 61), 

 is related to the Cretaceous genera Anogmius and some others that have small or minute teeth 

 clustered on the margins of the jaws and on the parasphenoid and other bones within the 

 mouth. 



The small size of the mouth in Albula appears to be a specialization which has involved 

 the reduction of the marginal teeth on both jaws and the enlargement of the premaxillae, 

 which, as in many more advanced teleosts, have crowded the maxillae out of the gape. 

 The dwindling of the mouth and the simultaneous elongation of the snout have, as it were, 

 dragged the lower end of the suspensorium forward and with it the attached inter- and 

 pre-operculars. The coronoid process of the dentary rises steeply, as in other short-jawed 

 isospondyls. The lacrymal also has been extended forward in correlation with the marked 

 increase in length of the snout. The surface of the snout is deeply pitted by enlarged 

 organs representing the rostral branch of the lateral-line canal; similar organs have left a 

 raised shelf along the upper suborbital border. 



The otolith of Albula vulpes, according to Frost (1925a, p. 155), is the most aberrant 

 form among the otoliths of Clupeoidea. However, it is approached in a certain peculiar 

 feature by that of Engraulis mystax. 



The Cretaceous genus Isteus, which is placed by Smith Woodward iri the Albulidae, 

 is regarded by him (1901. p. vii) as being "essentially identical with an imperfectly known 

 fish still surviving in the deep sea {Bathythrissa)." 



"The Cretaceous Clupeoids," writes Smith Woodward (1912, p. 254), "are chiefly of 

 interest on account of their precocious development. They do not differ much from some 

 of the Jurassic Leptolepidae but it is remarkable that so far back as the Lower Cretaceous, 

 both in Switzerland and in Brazil, some of them had already acquired the row of sharp 

 ventral ridge scales which are so peculiar a feature of the surviving Clupea and allied 

 genera," 



