August 24, 1906.] 



SCIENCE. 



247 



support of this purely hypothetical accelera- 

 tion; much is made of a suggestion that ac- 

 celeration is likely to occur because Lopho- 

 phyllum appears late (Carboniferous) in the 

 geological history of the Rugosa. The author 

 then produces what he considers evidence in 

 favor of a primary tetrameral plan. This 

 rests entirely upon a decalcified silicified speci- 

 men of Streptelasma profundum (Owen) in 

 which no doubt was left in the author's mind 

 that four of the strongest septa extended 

 farthest down into the base of the calice. No 

 sections are given, and no other suitable ma- 

 terial seems to have been at command. 



I, likewise, have in my possession numerous 

 decalcified silicified specimens of ;S^. pro- 

 fundum, the septal plan of one of which is 

 figured in Biol. Bull., June, 1905, p. 39, Some 

 of these are beautifully perfect, and present 

 all the appearances described by Gordon, but 

 one would scarcely think of using mere sur- 

 face views for the determination of a question 

 of such fundamental importance, especially 

 when more reliable means are available. Since 

 the publication of my paper in 1902 I have 

 made special efforts, with the assistance of 

 grants from the Carnegie Institution, to se- 

 cure from all parts typical species of the 

 Kugosa with perfect tips suitable for the in- 

 vestigation of this particular problem. Any 

 one familiar with the subject knows how very 

 rare such specimens are and the difficulties 

 which surround their examination. From my 

 study of these, by the method of grinding, I 

 can now state that in five different species I 

 have definitely determined the presence of six 

 primary septa, all equal, and situated at equal 

 distances apart. These species are Streptel- 

 asma rectum Hall, already figured in Biol. 

 Bull., June, 1905, Cyathaxonia cynodon E. & 

 H., Hadrophyllum glans (White), Hadrophyl- 

 lum pauciradiatum E. & H., and Microcyclus 

 discus Meek & Worthen. Many other species 

 have been investigated, but for one reason or 

 another their tips were unfavorable for show- 

 ing the primary septa, yet in tracing the de- 

 velopment of the later septa this so closely 

 agreed with the species mentioned that there 

 can be no reasonable hesitation in assuming 



that their primary septa were hexameral. In 

 no instance were there only four protosepta. 



Thus, with the addition of Lophophyllum 

 proliferum, the hexamerism of which Gordon 

 does not dispute, there are now six known 

 species of Eugosa each having six primary 

 septa, while not a single undoubted instance 

 of only four primary septa has been brought 

 forward. Moreover, the geological distribu- 

 tion of the species mentioned is so wide, from 

 the earliest to the latest appearance of the 

 Rugosa, that Gordon's main argument in 

 favor . of acceleration fails in its application. 

 Unless, therefore, fresh and weighty evidence 

 to the contrary should be forthcoming we are 

 reasonably justified in considering the pri- 

 mary hexamerism of the Rugosa as estab- 

 lished. 



The underlying significance of the primary 

 hexamerism of the Rugosa is that it admits 

 of the relationship of the group with other 

 Anthozoa being established. In the past the- 

 assumed tetramerism has led to many fanciful 

 suggestions. In my original paper I showed 

 conclusively that the Rugosa find their nearest 

 modern relatives among the zoanthid actin- 

 ians, and subsequent work, especially on the 

 f ossula, has but served to confirm this. Unless 

 Gordon can produce more acceptable evidence 

 than is contained in his paper under review 

 his contribution must be regarded as a retro- 

 grade step in our efforts to determine the 

 phylogenetic relationships of the Rugosa. 



J. E. DUERDEN. 



Rhodes Univeksitt College, 

 Grahamstown, Cape Colony. 



the source of the energy of cyclones. 



To THE Editor op Science: In the issue of 

 Science of May 5 last you were good enough 

 to publish a communication of mine suggest- 

 ing the source of origin of cyclones, cold 

 waves, and tornadoes. Since the appearance 

 of that article there has occurred to me the 

 suggestion of the derivation of the energy in- 

 volved in the movement of these bodies, or I 

 might better say, a mechanism of the action 

 of the prevailing westerly winds in accom- 

 plishing their movement, that has not hitherto 

 been suggested by any one, as far as I know. 



