Cooper.] - J *5- J [May Hi, 



Notes on some Land-shells of the Pacific Slope. By J. G. Cooper, M. D. 



{Read before the American Philosophical Society, May 16, 1879.) 



The recent publication of Vol. V of the "Terrestrial Air-breathing Mol- 

 lusks of the United States," etc., by W. G. Binney, as a "Bulletin of the 

 Museum of Comparative Zoology at Harvard College," forms a fitting oc- 

 casion for making some further observations, biographical and taxonomic, 

 on the species found west of the "Great Plains," which form the chief 

 boundary within our limits between the eastern and western groups of 

 species. 



It is to be regretted that Mr. Binney has not, had " time and inclination " 

 to improve on the classifications of Albers and Von Marten, which his own 

 original investigations have made quite inadequate to the subject (Preface, 

 p. iii). 



The many improvements made on the system adopted in the " Pul- 

 monata Geophila, " of Binney and Bland (Smithsonian Misc. Pub., 

 194, 1869), are very satisfactory, few of the errors there noted being 

 retained in this work, which is to a great extent a republication of that, 

 with additions from other sources, rendering it more complete as a manual 

 of the subject. The bad results of the habit of blindly following foreign 

 authorities is shown in the higher divisions adopted on p. 81, the first, 

 Agnatha, being founded on a negative character as to the jaw, while those 

 of the lingual teeth are not different in divisions B and C, and all of them 

 show that these parts are insufficient for classification alone, while they 

 lead to far more confusion of distinct forms than divisions founded only on 

 external characters. 



The labored investigations of the microscopists into the internal anatomy 

 has at last led to nearly the same results as a comparison of external forms, 

 as far as they prove a close connection to exist between the two groups of 

 characters, and we may hope that the less difficult system of classification 

 by external resemblances will in time resume its former importance, modi- 

 fied and improved by a knowledge of the entire structure of the animals. 

 The fallacy of making family divisions to depend on a few internal charac- 

 ters has been often shown, and is becoming more and more certain with in- 

 crease of investigation. I do not claim that the shells alone should guide 

 in classification, but, with the form of the animal, they should define the 

 higher groups, leaving the details of special organs to determine genera and 

 species. 



Genus Helix. 



Again following his authorities Mr. Binney uses ''Helix" as a compre- 

 hensive term, like Pfeiffer including in it every helicoid land-shell, and 

 like the French naturalists making genera by disintegrating it without 

 leaving a single original Helix. No other genus founded by the immortal 

 Linnaeus has so hard a fate, and it is to be hoped that at least one species 

 will yet be found to be a Helix. 



