June 15, 1906.] 



SCIENCE. 



921 



antinomia (Cat.). The two generic names 

 Pygope and Antinomia are employed, because 

 they are supposed to indicate two independ- 

 ent parallel genetic series, whose members dif- 

 fer in size and position of the perforation, and 

 in characters of the lateral margin. But there 

 is yet another series of diphyoids, typified by 

 Terehratula diphyoides, d'Orb. It is pointed 

 out that, although the species covered by the 

 name diphyoides are very like Pygope as now 

 used, yet they all differ in having particular 

 characters in the preperforate stage — a dorsal 

 ridge and a ventral sulcus. For this series 

 de Haan's MS. name Pygites is used; and it is 

 supposed that there are three genetic series of 

 diphyoids which have developed independently, 

 and that the remarkable perforate form, with 

 its two lobes joined, has been evolved three 

 times over. The three series develop from the 

 glossothyridoid, to the bifidate, to the perforate 

 (ordinary T. diphya) stage; and two series 

 are supposed to finish by losing all trace of 

 the perforation, the lobes completely coalesc- 

 ing (the imperforate stage), represented by 

 T. pileus, Brug. = T. triangulus, Val. in La- 

 marck. 



In compiling synonymies of the species in 

 the three genera there have been found two 

 other papers overlooked by Brachiopod bib- 

 liographers — one by E. Newman in the Zoolo- 

 gist, 1844, p. 6Y9, naming T. Duvali, and one 

 by CatuUo. S. S. Buckman. 



GEOLOGICAL SECTION OF NEW MEXICO. 



Until within the past year no connected 

 view of the geological formations of the New 

 Mexican region has been possible. From the 

 literature alone little of an exact sequence of 

 geological formations could be made out. 

 Since the work of the geological and mineral 

 survey of New Mexico, under the direction of 

 the School of Mines, at Socorro, has been 

 undertaken much new and much-desir^ in- 

 formation has been obtained, until now a very 

 satisfactory and correlated scheme of the rock 

 succession has been constructed. The section 

 is instructive on account of — (1) its com- 

 pleteness, (2) its easy parallelism with the 

 brtter known sections of other parts of the 



continent, (3) the great development of cer- 

 tain of the major formations, and (4) the 

 many great unconformities which represent 

 long erosion intervals. 



Nearly every one of the twenty-five larger 

 formations, those having a taxonomic rank of 

 series, are separated by marked unconformi- 

 ties. The recognition of these erosion in- 

 tervals explains many hitherto unsolved phe- 

 nomena regarding the relationships of the 

 various formations, and enables exact correla- 

 tions to be made in a way that is impossible 

 among the terranes of most other localities, 

 and largely without the use of organic re- 

 mains. The section is as follows : 



GENEEAL GEOLOGICAL SECTION OF NEW MEXICO. 



The most noteworthy features are the great 

 development of the Tertiary and Cretaceous 

 deposits, the presence of rocks of the Jurassic 

 horizon, the completeness of the Carboniferous 

 sequence, the representation of all systems of 

 the Paleozoic, and the differentiation of the 



