376 H. F. CLELAND THE TEACHING OF HISTORICAL GEOLOGY 



knowledge of the classification of the plants and animals which form the 

 basis for an important part of the work. Under the most favorable con- 

 ditions, the student may have had one or more courses in biology, but in 

 these courses he learned more about cells, heredity, and evolution than 

 about forms and their classification. One will be conservative in stating 

 that not one student in fifty who elects geology possesses a knowledge of 

 a classification of plants and animals that will be really helpful to him 

 in his study of historical geology. Such important Paleozoic animals as 

 brachiopods, trilobites, bryozoans, crinoids, cystoids, graptolites, and old- 

 style corals are given bare mention, if mentioned at all, in courses in 

 elementary biology. Consequently, biology as a prerequisite to historical 

 geology is of little value. It is because of this ignorance of those inver- 

 tebrates which must necessarily be discussed that every teacher of his- 

 torical geology heaves a sigh of relief when the Paleozoic is completed 

 or, at least, when the Pennsylvanian is reached. 



As a result of the student's ignorance of biological classification, he 

 has a vocabulary hurled at him, almost as soon as he begins his study of 

 historical geology, which discourages the earnest and frightens the dull, 

 and it is not until the Cambrian, Ordovician, and Silurian are passed 

 that the class begins to find solid ground. I am assuming that the course 

 is largely confined to the study of the classes and orders of animals and 

 plants, and that the student is not required to learn much about species 

 and genera. I think we too often fail to realize that even group names, 

 such as brachiopod, gastropod, and trilobite, do not immediately call up 

 a definite image to most students until quite late in the course, and con- 

 sequently when the teacher lectures about them or brings them into his 

 discussions he is not fully comprehended. Until each group studied does 

 call up a definite image to the student, he can not, of course, become 

 interested in the life of the past. An extreme example will illustrate this 

 difficulty. A well known geologist, an excellent teacher, was asked by a 

 student, during the study of the reptiles of the Mesozoic, if these animals 

 had skins when they were alive or if they were always skeletons. 



As the time allotted to historical geology in most colleges and univer- 

 sities is three hours a week for one semester, it is evident that the 

 teacher can not devote many lectures and laboratory exercises to the 

 teaching of classification and the descriptions of animals and plants. 

 One of two ways of teaching this necessary classification is used: the 

 teacher either gives preliminary lectures or laboratory work on the entire 

 classification, and thus quickly gets it out of the way before going on 

 with the substance of the course, or he takes it up a little at a time, as 

 the subject requires. When this latter method is followed he spends a 

 disproportionate time on the Cambrian and Ordovician, since in the dis- 



