214 TRANSACTIONS OF THE AMERICAN PHILOSOPHICAL SOCIETY 



Haplomi (Pikes, etc.) 



The pikes (Esocidse) and their immediate allies the Umbrid^ are regarded by Wood- 

 ward as "essentially freshwater Scopeloids." Starks (1904a, 1926a) holds that the three 

 main families of the group, the Esocidse, the Umbridse and the Poecilildse "have either 

 widely diverged from each other or are not of the same line of descent"; also (1926a, p. 203, 

 footnote) that "If the order Cyprinodontes [Microcyprini] is recognized as distinct from the 

 order Haplomi, the family Esocidse should be raised to co-ordinate rank. It has little In 

 common with the Umbridae." Starks (1904a) accordingly divided the order Haplomi into 

 three superfamilies: (I) Esocoidea, containing the Esocidae and the Umbridse; (2) Poeciloi- 

 dea, containing the Poeciliidse; (3) Amblyopsoidea, containing the Amblyopsidae. That 

 the Haplomi in the restricted sense are well separated from the Microcyprini and closely 

 related to the Isospondyli is indicated by the comparative study of the otoliths by Frost 

 (1926, p. 465). In Esox the sagitta resembles that of the isospondyls Megalops cyprinoides 

 of the Clupeoidea and Gonostoma of the Stomiatoidea but it is more highly specialized, 

 while in the typical Microcyprini this otolith, although widely varied, seems to start from 

 a peculiar "Alicrocyprinid" type. 



Boulenger (1910, p. 606) referred to the order Haplomi a large series of families, many 

 of them having no apparently strong claims to close relationship with the Esocidae. 



Tate Regan (1909a, p. 83) restricted the Haplomi to the Umbridae, Esocidae and 

 Dallildae, raising the Poecillldae and its allies to ordinal rank as Microcyprini. 



Evidence of the relatively close relationships of both the Haplomi and the Inlomi to 

 the typical Isospondyli (to which group they were referred by Smith Woodward) is afforded 

 by the form and arrangement of the branchiostegal rays. "In the Haplomi (Esox, Umbra 

 and Dallia)," writes Hubbs (1919, p. 66), "but not in the poecilioid fishes which have been 

 confused with them, the branchiostegals are like those of the Isospondyli. In the Inlomi 

 (the Synodont fishes and their allies) the branchiostegals vary greatly in number (from 

 six to twenty, four to eight attached to the suture between ceratohyal and epihyal, two to 

 twelve below the suture); in Plagyodus the uppermost ray, as in the Isospondyli, is not 

 wholly concealed, but in most of the genera several of the upper rays are covered by the 

 opercula; when the rays are numerous several of the upper ones are closely approximated 

 basally." 



Esox. — If we consider the skull of the muskellonge, Esox musquinoni (Fig. 95), with 

 special reference to its "adaptive" features, we shall note that the dominant physiological 

 feature Is the very large lower jaw with its row of high, well-spaced, great lanlary teeth 

 pointing upward and inward, in front of which is a series of small sharp teeth arranged 

 along the upward curve of the undershot jaw. Obviously the big teeth pierce the prey, 

 which Is held fast by the chevaux-de-Jrise of smaller inwardly-directed sharp teeth arranged 

 in long rows on the dermopalatlnes and vomer. The premaxillary teeth are practically 

 vestigial. The maxillary, although edentulous, serves to press the prey against the lower 

 dagger-like teeth. The supramaxlllary is a souvenir of much earlier times. As the 

 dominant elements of the lower jaw are the great lanlary teeth on the sides, so the most 

 important elements of the upper jaw are the large dentigerous areas on the dermopalatines 

 and entopterygoids, which run in nearly parallel antero-posterior tracts. These are sup- 

 ported and braced dorsally by the large true palatines and posteriorly by the ectopterygold, 

 quadrate and metapterygoid, which also receive the heavy thrusts from the lower jaw and 

 transmit the whole load to the strongly-braced hyomandibular. 



