ZOOLOGY. 371 



development which have resulted in the completely ossified and highly 

 organized Siluroids now existing." 



:,We give these results of Mr. l)a^•is' investigation on account of the 

 importance of the question involved, but it seems best to add that there 

 can be no close relatioushii) between the Teleosts and the Selachians, 

 and that the question as to the relationship of the palieozoic fishes can 

 only be ascertained after the examination of specimens in a far more 

 satisfactory condition than any that have yet been found. 



THE PLATYSOMIDS AND TALiEONISCIDS. 



Two of the most frequently occurring groups of fishes occurring in the 

 paleozoic formation are the Palseoniscidie and the Platysomidtie. The 

 affinities of these types have been but little understood heretofore, and 

 Dr. R. H. Traquair has therefore been led to a re-examination of the 

 subject.* He has reached the following conclusions: 



"1. That the Platysomidiie are specialized forms, which have, if the 

 doctrine of descent be true, been derived from the Pala3oniscidffi. Their 

 structure presents us simi^ly with a modification of the Palasoniscoid 

 type; and wherever the Pala?oniscida3 are placed in the system, thither 

 the Platysomidoe must follow. 



"2. The resemblances between the Platysomidaj and the Dapediidte 

 and Pycnodontidte are mere resemblances of analogy and not of real 

 affinity. The Dapediidce are related not to the Palfeoniscidae or Platy- 

 somidtie, but to the other semiheterocercal Ganoids of the Jurassic era 

 {Lejndotns, &c.); and the Pycnodonts are higly specialized forms, whose 

 general affinities point in the same direction." 



Professor Traquair concludes that the PalfcouiscidiE and Platysomidne 

 belong to the "Acipenseroid sub-order of Ganoids." 



The characters ascertained to distinguish the Platysomidcne and Pal- 

 reoniscidse scarcely appear to warrant the conclusions of Professor Tra- 

 quair. Professor Cope, Indeed, has been led by the consideration of 

 Professor Traquair's studies to a very different result, and one approx- 

 imating, apparently, more to nature. Copef has proposed to differentiate 

 the forms in question as representatives of "a distinct group of the same 

 rank as those [he has] called orders," and given to it the imme Lysoptert. 

 They are defined as "actinopterous fishes, with the median fin-rays not 

 joined to the interhtemal and interneural bones, and not coinciding with 

 them in number; and without suboperculum." 



ON THE SEXES OF THE EELS.f 



As is generally known, the subject of the reproduction of the eels was 



* Traquair (Ramsay H.). The Platysoiuidte. Ann. Mag. Nat. Hist., (5), vol. vi, pj). 

 97, 98. On tlie Structure and Affiuities of the Platysomidaj. Trans. Hoy. Soc. Edin- 

 hiirgh, vol. xxix, pp. 343-391, pi. 3-6. 



t Cope (E. D.). Traquair ou PlatysomidiB. Am. Nat., vol. xiv, jip. 439, 440. 



t Cattle (S. Th.). Ueber die Geuitalien der mihinliclieu Aale und ihre sexual Unter- 

 Bclieide. Zool. Anz., vol. iii, pp. 275-279. (On the Genitalia of male Eels and their 

 eexual characters. Proc. U. S Nat. Mus., vol. iii, j>i^. 280-284.) 



