N. A. INVERTEBRATE PALEONTOLOGY. 739 



external coverings was gained. The author says that there can be no 

 question that the trilobite had foes stronger than himself, against whom 

 he found defense only in his chitinous armor," but he says nothing of 

 the necessity of weapons of attack in these supposed foes. 



Morris, Charles. — Attack and Defense as Agents in Animal Evolu- 

 tion. Froc, Acad. Nat. ScL, Philad., vol. — , pp. 385-392. December, 

 1885, Philadelphia. 



Early fossilization is due to the preservation of the dermal skeletons 

 of animals of considerably advanced organization, and those were proba- 

 bly preceded during a long era by soft- bodied forms of low organization. 

 Yet, after the advent of armored animals, it is probable that the seas 

 were still tenanted by numerous soft-bodied forms, mainly swimmers, 

 the progenitors of the many naked ocean swimmers which still exist. 

 Later the tendency is no longer to assume armor, but to throw it off 

 and return toward the unprotected condition. Finally, in the human 

 species, even the covering of hairs is nearly lost, and in external condition 

 the highest form of animal life approaches the lowest. The armored 

 cephalopods have gradually disappeared till only the Nautilus remains. 

 The unarmored forms have rapidly increased until they abundantly 

 people the modern seas. The changes described have taken place under 

 the influence of one of the most active' agents in evolution, that of the 

 reciprocal influence of attack and defense on animal structure. Thus 

 we seem to perceive four successive ideas emerging into prominence in 

 the development of the animal kingdom. In the primaeval epoch it is 

 probable that only soft-bodied animals existed, and the weapons of as- 

 sault were the tentacle, the thread cell, the sucking disk, and the like 

 unindurated weapons. At a later period armor became generally 

 adopted for defense, and the tooth became the most efficient weapon of 

 attack, till later armor was discarded, and flight or concealment be- 

 came the main method of escape, and swift pursuit the principle of at- 

 tack, while claws were added to teeth as assailing weapons. Finally, 

 mentality came into play, intelligence became the most efficient agent 

 both in attack and defense, and a special development of the mind be- 

 gan. 



The article is so condensed as to render it difficult to give a brief sy- 

 nopsis of it. 



Meyer, Otto.— The Genealogy and the Age of the Species in the South- 

 ern Old-Tertiary. Amer. Jour. ScL, 3d ser., vol. xxix, pp. 457-468; 

 vol. XXX, pp. GO-72, and 421-435, figs, a-c, on p. 70. June, July, and 

 December, 1885. New Haven. 



The author considers that the succession is just the contrary from 

 what has ordinarily been supposed, the Vicksburg being the oldest, 

 and the Claiborne the most recent formation. The article is divided 

 into three parts. 



