Mat 22, 1908] 



SCIENCE 



825 



the length of the smallest known sirenian 



fetus; gyre preferred to 



" convolution " 



To the Editor of Science: In the Octxjber 

 issue of the American Naturalist, under " Sci- 

 entific Exhibits at the Seventh International 

 Zoological Congress," on p. 633, the fetal 

 manatee shown by me is said to be " ap- 

 proximately an inch and a half long." Since 

 this is supposed to be the smallest known 

 Sirenian fetus it is proper to state that from 

 the root of the flexed tail to the top of the 

 flexed head, allowing two mm. for the de- 

 pression caused by the removal of the brain, 

 the present length is 53 mm., say two and one- 

 eighth inches. It has shrunk about two mm. 

 since the measurements recorded in the 

 American Journal of Science and Arts, 

 August, 1875, where also various aspects are 

 represented upon Plate VIII. In accordance 

 with the criterion applied to the developing 

 human being by Minot (" Embryology," p. 

 391) this specimen should be called fetus 

 rather than emhryo, because the tail is un- 

 mistakably that of a manatee notwithstanding 

 the marked flexures of both ends of the body 

 and the resemblance of the head to that of a 

 horse or other ungulate. 



On p. 662 it is said that I " exhibited 

 photographs of human cerebral convolutions." 

 Do not think me over-particular in disclaim- 

 ing responsibility for the last word. I would 

 no more use " convolution " for gyre than 

 ^' conflagration " for fire. The choice was 

 made deliberately in 1881, and published on 

 page 133 of the issue for March 26 of Science, 

 (the original periodical of that name, of which 

 only three volumes were published). It has 

 been declared upon several subsequent occa- 

 sions. It constitutes one of many cases of 

 identity between my neural terms and the 

 B.N.A., although the framers of the latter 

 Tiad not the grace to acknowledge the priority 

 of nearly the fourth of a century. 



Burt G. Wilder 



Ithaca, N. Y., 

 April 7, 1908 



AMETHYSTINE GLASS 



In connection with the interesting informa- 

 tion given in Science, Eebruary 7, p. 239, 



it may be worth while to call attention to the 

 fact — first pointed out to me by Mr. Irish, of 

 the normal school at Tempo, Arizona — that 

 ordinary bottle glass, when left exposed on the 

 ground out-of-doors in the arid southwest, as- 

 sumes a strong purple or amethystine color. 

 This I have observed in Arizona, New Mexico 

 and Colorado. Dr. Shedd, when professor of 

 physics at Colorado College, examined some 

 of this glass which I had collected at Colorado 

 Springs, and found that the color was dis- 

 charged by heat. Many years ago, Earaday 

 made some experiments with glass, noticing a 

 similar change of color; but I have not seen 

 any recent literature upon the subject. 



t. d. a. cockerell 

 Univeesitt of Colorado 



SPECIAL ARTICLES 



SOME NOTES ON MALACOLOGICAL NOMENCLATURE 



Two years ago I published a small paper 

 on this matter.' On some points my eminent 

 and most competent friend. Dr. W. H. Dall, 

 does not agree with me, and I hope that these 

 lines may contribute to concert between us. 

 This would be the more desirable, as Dr. Dall 

 without any doubt is actually the first among 

 all the living malacologists whose knowledge 

 extends to actual moUuscan faunas as well as 

 to extinct ones. Also the divergence of Dall 

 and myself is not one of principle, but only 

 caused by a difPerent interpretation of the 

 international rules. 



Dr. Dall during the last years has made 

 many efiorts toward establishing names of 

 ancient authors, more or less forgotten. The 

 question in this case can not be that of the 

 more or less convenience in accepting such 

 names, but whether it is necessary to have 

 no other rules for our manner of proceeding, 

 than consequence and logic. Therefore we 

 accept the most disturbing changes, but only 

 in the case of true necessity, and this is not 

 the case at all with such authors as Martyn, 

 Humphrey, Link, Bolten, Morch and others. 



The international rules say in article 25: 



The valid name of a genus or species can be 

 only that name under which it was first desig- 



' Naohrichtsbl. der Deutsch. Malacozool. Ges., 

 1906, pp. 1-12. 



