THE MOBMTEIDiE, KOTOPTEEIDiE, AWD HYOBONTIDiE. 213 



families are so conflicting, that any phjlogenetic arrangement 

 based upon them is out of the question. The three families 

 must remain, as hitherto, the terminals of a radiating system. 



As Boulenger points out (Proc. Zool. Soc 1898, p. 778), the 

 Mormyridse cannot rightly be grouped with the Ostariophysi of 

 Sagemehl as Jordan and Evermann (Fish. INT. Amer. i. 1896, 

 p. 114) have done, since they possess no Weberian ossicles nor 

 other modification of the anterior vertebrae. The absence of a 

 separate symplectic in both Mormyroids and Siluroids is 

 evidently nothing more than a matter of convergence : the 

 symplectic is absent also in the Eels. The study of the skull 

 of the Mormyroids shows also that they can have no close 

 affinity with the Esocidae, with which family Johannes Midler 

 associated them. According to Boulenger the nearest allies 

 of the Mormyroids are to be found in the Albvilidse, as suggested 

 by Valenciennes in 1846 (Hist. Nat. Poiss. six. p. 225 and 

 p. 324). 



I regret that the study of the skull brings forward no 

 evidence in favour of this contention. While the Morrayridae 

 are highly specialized in certain respects, it must be admitted 

 that they retain some primitive features. Of these, the presence 

 of an orbitosphenoid and the meeting of the parietals in the 

 median line are two, but they do not point to any closer 

 resemblance between the Mormyridse and the Albulidse thkn 

 with any other primitive family. 



The presence of parasphenoidal teeth in most Mormyroids, in 

 which respect the family agrees with the Albulidse, may be 

 regarded as another primitive feature retained by both families 

 from the ancestral Teleosteans, a feature which might well be 

 retained by two even strongly diverging families. Although ia 

 Alhula there is no limitation of the freedom of lateral movement 

 of the hyopalatine arch, the arch is certainly in fairly close 

 contact with the cranium along the whole of its upper edge,, 

 and in this respect exhibits some resemblance to the condition 

 found in the Mormyridse ; but the feature is an adaptive one,, 

 not uncommon in fishes that have a parasphenoidal and lingual 

 dentition well developed, or that can bring the floor of the 

 mouth forcibly against the palate. 



The bounding of the upper border of the mouth by the 

 premaxillse alone and the absence of teeth on the maxillse are 

 specialized characters affected by numerous families of Tele- 



