44 



SCIENCE. 



[Vol. VL, No. 128. 



produces gas, since other factors have to be consid- 

 ered, as there stated; but, with the facts before us, it 

 would certainly prove a great saving of capital in 

 the search for gas, if operations were confined to the 

 crests of the anticlinals; and I fail to perceive how 

 Mr. Ashburner's fears for the 'misleading ' character 

 of my article can be realized. I. C. White. 



Mountain-Lake Park, Md., July 11. 



A rare dolphin. 



On the 3d of June the national museum re- 

 ceived from Messrs. Warren & Co., fish-dealers 

 in Pensacola, Fla., a very beautiful and highly in- 

 teresting dolphin, which was captured in the Gulf 

 of Mexico, The upper surfaces of the body were 

 dark slate-color, sprinkled with whitish spots about 

 the size of a cent; while the under surfaces were 

 white, spotted with dark gray. The species belongs 

 to the genus Prodelphinus, — a genus closely allied to 

 Delphinus, of which the dolphin of the ancients, D. 

 delphis, is the type. Numerous species of Prodel- 

 phinus have been described from single skulls, but 

 scarcely any thing is known regarding their external 

 forms or relationships. The recent discovery of great 

 schools of this spotted species in the Gulf of Mexico, 

 and also, still more recently, by the U. S. fish-commis- 

 sion steamer Albatross, off the coast of North Caro- 

 lina, gives the hope that we may soon be able to clear 

 away the obscurity now resting upon the genus. 



F. W. True. 



U. 8. national museum. 



The scenery of Arizona. 



The unique character of western Arizona leads me 

 to add a few words to the article of ' A. G.' in your 

 issue of June 26. Only ignorance of tlie extreme at- 

 tractiveness of this almost unexplored region explains 

 the fact that so few tourists find their way thither. 



My chief object in addressing you is to mention an 

 easily made excursion from Flagstaff, fifty miles to 

 the south, through Oak-Creek valley, and into the 

 valley of Beaver Creek, to Fort Verde. Oak Creek is 

 more like a White-Mountain stream than any other 

 creek that I have seen in Arizona. The valley 

 broadens to a considerable width, after dropping 

 down a thousand feet or more from the mesa upon 

 which the creek rises, and is enclosed by lofty bluffs 

 of sandstone, the lower half of which is deep red, 

 while the upper half is bright gray. The line of 

 demarcation between these colors is remarkably 

 distinct. These rocks, of mesozoic age, have been 

 sculptured by eroding waters in the most wonderful 

 manner. 



This region is easily explored by following the trails 

 on horseback. The rocks have not, of course, the 

 sharpness and steepness of limestone mountains (the 

 Alps, for instance); but it has never been my lot to 

 view scenery elsewhere so graceful and picturesque. 

 I feel at liberty to speak with enthusiasm on this 

 subject, for none that visit Oak-Creek valley will 

 come away disappointed. K. Spaulding. 



Montclair, N.J., July 4. 



The classification and paleontology of the 

 U. S. tertiary deposits. 



Although much tempted to make some comments 

 on the remarkable statements of Dr. Otto Meyer rela- 

 tive to the south-western tertiaries, in his late article 

 in the American journal of science, I had determined 

 to keep silence until the second part of his work, pre- 

 sumed to contain the stratigraphical evidence he 

 might have to present, should have appeared. In 



view, however, of Heilprin's notice of the subject in 

 the issue of Science of June 12, I desire to enter a 

 caveat on both sides of the question, as one who has 

 spent eighteen years, more or less, in the study of these 

 formations. I emphatically agree with Heilprin as to 

 the impossibility of subverting the cumulative strati- 

 graphical evidence to the effect that the relative super- 

 position of the several principal stages — the Burstone, 

 Claiborne, Jackson, and Vicksburg groups — cannot 

 be otherwise than as heretofore ascertained in hun- 

 dreds of localities, by others as well as by myself ; even 

 supposing that the geographical distribution, with 

 relation to the progressive elevation of the continent, 

 could leave any doubt in the premises. I recall to 

 mind that years ago I had occasion to repel a simi- 

 lar attempt, on the part of Mr. Conrad, to subvert 

 the relative position of the Jackson and Vicksburg 

 groups upon supposed paleontological evidence (see 

 ' Remarks on the Shell Bluff group of Mr. Conrad,' 

 in American journal of science, 1867). As Dr. Meyer 

 seems to have been on the spot, and must have seen 

 the Jackson strata disappearing beneath those of the 

 Vicksburg group (if he ever descended Pearl River 

 below Jackson), and the Claiborne and Jackson van- 

 ishing beneath the same and the Grand Gulf rocks (if 

 he descended the Chickasawhay River), apart from 

 what is proven by the exposures on the Tombigbee 

 and Alabama rivers in the state of Alabama, his pre- 

 diction that ' probably ' the whole series might have 

 to be turned upside down, is strongly suggestive of 

 the periodic attempts to subvert the ' Copernican 

 system ' of astronomy. 



Aside, however, from Dr. Meyer's stratigraphical 

 vagary, I strongly sympathize with his views in re-^ 

 spect to the transition of so-called species, mostly 

 named by Conrad, from one of the stages to another; 

 I repeatedly called Conrad's attention to the impos- 

 sibility of maintaining a number of his distinctions, 

 especially among the genera Pleurotoma, Fusus, Vo- 

 luta, Corbula, Venericardia, and others; and finally, 

 finding that every variation, clearly apparent to me 

 as such, was by him interpreted as a new species, I 

 ceased to send him fossils from the south-western 

 formations, in order not to swell uselessly the already 

 long list of spurious species. In a number of cases 

 Dr. Meyer has observed and recorded precisely what 

 I have long known to be the fact, — that oftentimes 

 from two to five of Conrad's species are mere varia- 

 tions, easily recognized as such when the rich mate- 

 rial is seen on the spot and in numerous localities. 

 That Dr. Meyer has in all cases judged correctly, I 

 am of course unprepared to say; but I emphatically 

 hope that a critical revision of the tertiary and upper 

 cretaceous fauna of the south-west will soon be made, 

 with a view to what we have learned on the subject 

 of evolution since Lea's and Conrad's time, and that 

 the host of varieties now cumbering our tertiary 

 check-lists in the guise of species will be reduced to 

 something like a comprehensive view by a master 

 hand. I doubt if there exists a finer opportunity 

 for observing the evolution of marine species in ter- 

 tiary times than is presented by the minutely differ- 

 entiated formations of Mississippi and Louisiana. 



E. W. HILGA.RD. 



Berkeley, Cal., June 22. 



The ginkgo-tree. 



A large and remarkably fine specimen of Salisburia 

 adiantifolia was in fruit on the Landreth estate, near 

 Bristol, Penn., during September last, — an annual 

 and by no means uncommon occurrence, according to 

 the proprietors. Winthrop E. Stone. 



Mass. ag'l exp't station, July 6. 



