288 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



Vertebrate, however low its structure may be. But, we 

 repeat, the divergence of Branchiostoma from the other 

 Vertebrates is very great; and there can be little, if any, 

 doubt that if we desire to express the degree of relationship 

 of animals by taxonomic devices and in our nomenclatures, 

 and accept the word "class" for groups like the Birds, on 

 the one hand, and the Reptiles, on the other, we must as- 

 suredly entitle Branchiostoma with class rank, and, proceed- 

 ing in the same direction, even contrast it with all the other 

 Vertebrates. 



As to the combination of the Tunicates with the Verte- 

 brates, there may be room for more difference of opinion ; 

 but whatever may be the ultimate verdict, it will probably 

 be regarded by the great majority of naturalists as prema- 

 ture. The classification proposed by Professor Lankester is 

 rather different in other respects from that generally adopt- 

 ed. Professor Lankester has for the first time differentiated 

 as classes the Hyperotreta (Myxines) and Hyperoartia (Lam- 

 preys), which have been usually regarded as simple orders 

 of one class the Marsipobranchiates. The differences be- 

 tween the Hyperotreta and Hyperoartia, as well as those 

 between the Pisces, as represented by the Polypterids, and 

 the Dipnoi are generally regarded, in fact, as of less system- 

 atic value than those between the true Fishes and the Se- 

 lachians. The groups of placental mammals called "sub- 

 classes" have also for the first time been entitled such by 

 Professor Lankester. Earlier names of some of the other 

 groups are indicated within brackets. 



Origin and Relations of the Vertebrates. 



The questionable character of the union of the Tunicates 

 with the Vertebrates in a group differentiated from and co- 

 ordinate with other primary divisions of the animal king- 

 dom has been indicated. A distinguished German naturalist, 

 Professor Carl Semper, in the past year, has even contended 

 that the relations of the Vertebrates are most intimate with 

 the Articulates, and revives, but with some essential modifi- 

 cations, the old view of Geoffroy St.-Hilaire, that the Artic- 

 ulates are homologous with Vertebrates, reversed and pro- 

 gressing with back downwards. Semper maintains that the 

 Arthropod Articulates and Vertebrates are descendants from 



