.xii,] THE GENEALOGY OF ANIMALS. 317 



connect the Trilobita and the Copepoda with the 

 Xiphosura. But the Xiphosura have such close mor- 

 phological relations with the Arachnida, and especially 

 with the oldest known Arachnidan, Scorpio, that I can- 

 not doubt the existence of a genetic connection between 

 the two groups. On the other hand, the Branchiopoda 

 do, even at the present day, almost pass into the true 

 Podophthalmia, by Nebalia. By the Trilobita, again, 

 the Archicarida are connected with such Edriophthal- 

 . mia as Serolis. The Stomapoda are extremely modified 

 ; Edrioplithalmia of the amphipod type. On the other 

 , side, the Isopoda lead to the Myriapoda, and the latter 

 to the Insecta. Thus the Arthropod phylum, which 

 suggests itself to me, is that the branches of the 

 , Podophthalmia, of the Insecta (with the Myriapoda), 

 and of the Arachnida, spring separately and distinctly 

 from the Archseocarid root and that the Zb#a-forms 

 occur only at the origin of the Podophthalmous branch. 



The phylum of the Vertebrata is the most interesting 

 of all, and is admirably discussed by Professor Haeckel. 

 I caa note only a few points which seem to me to be 

 open to discussion. The Monorhina, having been 

 developed out of the Leptocardia, gave rise, according 

 to Professor Haeckel, to a shark-like form, which was 

 the common stock of all the Amphirhina. From this 

 " Protamphirhine " were developed, in divergent lines, 

 the true Sharks, Kays, and Chimcerce ; the Ganoids, and 

 the Dipneusta. The Teleostei are modified Ganoidei. 

 The Dipneusta gave rise to the Amphibia, which are 

 the root of all other Vertebrata, inasmuch as out of them 

 were developed the first Vertebrata provided with an 

 amnion, or the Protamniota. The Protamniota split 

 up into two stems, one that of the Mammalia, the 

 other common to Reptilia and Aves. 



The only modification which it occurs to me to suggest 



