336 Dr. C. Liitken on the Limits and 



bility tliat future discoveries may some day demonstrate to us 

 these still unknown bonds*; nor must we forget that it is not 

 many years since naturalists did not hesitate to refuse a place 

 among the Ganoids to tho. AsjndorhyncM, the CosIacantJn\ and 

 the FycnodonteSj which we noAV arrange without hesitation 

 among the undoubted Ganoids. 



a. In the tirst place, the Le-pidosirens or Protopteri^ classed 

 by some writers of incontestable authority with the Ganoids, 

 but most frequently regarded as forming a peculiar subclass 

 [Dipyioi)j will form, in my opinion, only an aberrant tribe or 

 a suborder of the Physostome Teleosteans, to be placed in the 

 immediate vicinity of the Ganoids and particularly of the 

 Crossopteri (Phaneropleuron^ for example). 



h. Then the Sturgeons are also Physostome Teleosteans, 

 which should be arranged as near as possible to the Chon- 

 drosfei, between the latter and the Ganoidei, with which, 

 however, they must not be united f. 



c. The Amice approach the Ganoids and Chondrosteans by 

 a number of remarkable anatomical peculiarities ; but we 

 should not be more justified in classing Anna with the Ganoids 

 than in arranging the Sturgeons among the Selachia. It is a 

 special type, belonging to the true Physostome Teleosteans, 

 leading towards the Ganoids, but not attaching itself to them. 

 Moreover the removal of this group from the suborder Ga- 

 noidei will but slightly modify the palasichthyological system, 

 as it includes only a small number of forms {Xotieus, 

 Cycluncs, Amtojysis), which perhaps ought to be united with 

 Amia itself. 



d. There is also no positive reason for arranging the Juncssic 

 Teleostei [Leptolepides^ Megaluri^ and Catari) either with 

 the Amiida3 or with the Ganoidei. If we consult the synthetic 

 method, it will lead us rather towards the Haleco'ides — that is 

 to say, the Salmons, Herrings, and Clupesoces. They are 

 consequently true Physostome Teleosteans, and, with the ex- 

 ception of the Belonorhjnchus &c. of the Trias, the most 

 ancient representatives of this suborder. Moreover it will be 

 impossible to separate the three families above named from 

 each other ; those avIio, with the modern pala3ichtliyologists, 

 Heckel, Wagner, and Pictet, place the Leptolepides among the 

 true Teleostei, will be obliged likewise to place there the 

 Megaluri and Caturi, notwithstanding the fulcral scales bor- 

 dering their fins ; the filiation of the species, the crossing of 



* At this moment the journals inform us of the discovery in Australia 

 of a new genus of freshwater iish, intermediate between the Lcpidosirens 

 and the I'alajozoic Dipfo-i ! [See papers by Dr. Giinther and Messrs. Han- 

 cock Sc Atthey in the March Number of tliis Journal. — Ed. Ann. Nat. Hist.] 



t The affinities of the fossil genus Chondrosteus are perhaps still 

 doubtful. 



