458 Scie^itific Intelligence. 



Professor W. B. Scott, in the lecture on " Paleontology as a 

 Morphological Discipline," though presenting no original investi- 

 gations, appropriately calls the attention of biologists to the 

 importance of paleontological studies toward the solution of the 

 perplexing problems of biology. He mentions " one or two 

 principles which stand out with especial clearness as the deduc- 

 tions drawn from paleontological sludy of phylogenetic series. 

 These are (a) "" Evolution is ordinarily a continuous process of 

 change by means of small gradations," although "this does not 

 imply that the rate of change was always uniform, — it probably 

 was not, — or that a sudden alteration of conditions may not bring 

 about discontinuity, or per saltum development." 



(b) " Development is, in most instances, direct and unswerv- 

 ing." .... 



(c) " Parallelism and convergence of development are much 

 more general and important modes of evolution than is commonly 

 supposed. By parallelism is meant independent acquisition of 

 similar structure in forms which are themselves nearly related, 

 and by convergence such acquisition in forms which are not 

 closely related." This observation leads the author to " empha- 

 size the necessity of founding schemes of classification upon the 

 totality of structure, and of determining the value of character- 

 istics, whether they are primitive or acquired, divergent, parallel, 

 or convergent, before attempting to assign them their proper 

 toxonomic value." h. s. w. 



4, The Dinosaurs of JSForth America; by O. C. Marsh. 

 Extract from the Sixteenth Annual Report of the U. S. Geolog- 

 ical Survey, pp. 133-414, 66 cuts in text, plates ii-lxxxv. Wash- 

 ington, 1896. — The Dinosaurs are by far the most prominent 

 group of vertebrates of geologic times, excelling all other groups, 

 not only in size, but also in degree of specialization. Their 

 development is confined strictly within the limits of the Mesozoic, 

 and, therefore, in tracing their history through the Triassic, 

 Jurassic, and Cretaceous, their rise, culmination, decline, and 

 extinction are fully recorded. 



In the present memoir, the arrangement of the subject is mainly 

 geological. The Diuosatirs are recognized as a subclass, embrac- 

 ing the three orders Theropoda^ Sauropoda, and Predentata. Of 

 these, the first were carnivores and the others herbivores. The 

 Predentata are again divided into three suborders : {a) the 

 Stegosauria, Dinosaurs more or less protected with dermal plates ; 

 {h) the Ceratopsia^ huge horned forms; and (c) the Ornithopoda^ 

 Dinosaurs with bird-like characters. 



In the Triassic, all the best-known species belong to the carniv- 

 orous order Theropoda. Abundant evidences of the herbivorous 

 forms are found in the footprints so common in the Connecticut 

 sandstone, but as yet no distinctive teeth or bones have been 

 discovered there. 



Among the Jurassic Dinosaurs, the diminutive JSallopus, the 

 small Coelarus^ and the ferocious AUosaurus and Ceratosaurus are 



