1098 The American Naturalist. [December, 
cord is more like that of Chilopods than that of any other Chilognath ; 
the eye has a lens approximating that of Scutigera, the hypodermis cells 
forming a sort of diaphragm, and the crystalline cone cells being 
arranged in groups. Heathcote concludes that Polyxenus has preserved 
traces in its anatomy of descent from the common ancestor of both 
Chilopods and Chilognaths, ''such ancestor being related to the 
Archipolipoda" [sic.'] He also regards the Myriapods as having a 
Peripatus-like rather than a Thysanuran ancestor. 
The Position of the Csecilians. — Dr. P. Sarasin gives ^ a brief 
resume of the work done by himself and his brother upon the develop- 
ment of Ichthyophis glutinosus. The embryos pass through stages which 
are clearly to be regarded as Perennibranchiate, and Derotreme stages, 
Sarasin fully recognizing the similarity between- the embryos ot 
Amphiuma and Ichthyophis first pointed out by Ryder. In short the 
result is that the Caecilians are to be regarded not as a distinct Batra- 
chian order, but in reality as apodous Urodeles. Although the devel- 
opment of the Perennibranchiate will show the affinities of the Batra- 
chia better, the Sarasins recognise Ganoid relationships in the fact that 
the young Caecilian has a spiral valve, while in the ear a condition ot 
the ductus endolymphaticus is transitory which is permanent in the 
Ganoids. On the other hand Reptilian affinities are recognised in the 
large yolked egg, in the great ossification and extensive articulation of 
the skull, the condition of the brain, the two aortic arches, a Jacobson's 
organ of the Reptilian type. The Stegocephali are regarded as highly 
important in the line of phylogeny. 
The Dolphins.— Mr. F. W. True has recently reviewed the Dol- 
phins of the world.8 He has studied not only the collections of the 
United States biit also those of the chief museums of England, Paris, 
Leyden and Louvain. The result is, that many forms previously re- 
garded as distinct are merged in synonymy, and for the whole world 
but sixty-two species are recognized, arranged in the genera Sotalia, 
Steno, Tursiops, Delphinus, Prodelphinus, Tursio, Lagenorhynchus, 
Sagmatias, Feresa, Cephalorhynchus, Neomeris, Phocaena, Orcella, 
Grampus, Globiocephalus, Pseudorca, Orca, Delphinapterus, and Mon- 
odon. The genus Pontoporia is not regarded as belonging to the ^ 
family Delphinidae. The whole work is accompanied by two keys, one 
based upon external, the other upon cranial characters. The North 
American species recognized areas follows : — Sotalia tiuuxiQ Florida), 
'ersamml., 1889. 
