June 4, 1909] 



SCIENCE 



917 



animal and plant life which are peculiarly adapted 

 to the use of the investigator. The laboratory 

 offers no courses of instruction, being solely for 

 the use of investigators. The old Tide-mill col- 

 lecting ground and samples of some of the more 

 important animals and plants to be found tnere, 

 were illustrated. The geology of the Harpswell 

 region uas not been worked up and this presents 

 interesting questions, especially in glacial geology. 

 The speaker pointed out the advantages ottered by 

 the laboratory over those of our other marine 

 stations. 



Early Developmental Stages in Recent and Fossil 



Corals: Professor A. W. Geabau. 



Paleozoic corals show in their septal develop- 

 ment a fundamental tetrameral plan. This is 

 persistent in the earliest known forms, but be- 

 comes masked in later species by the secondary 

 assumption of radiality. The development of 

 mesenteries of modern Hexacoralla shows a sim- 

 ilar order of appearance. Pairs of mesenteries 

 develop in succession in bilateral disposition. 

 From the position of the muscle strands they are 

 either dorsads (musculature turned dorsal-ward) 

 or ventrads. The first and second pairs are ven- 

 trads. The third (ventral directive) is a pair of 

 dorsads, the fourth (dorsal directive) a pair of 

 ventrads. The fifth and sixth pairs are dorsads 

 forming with the first and second pairs four false 

 pairs of " braces." After that the mesenteries 

 appear in compound pairs, a pair of dorsads and 

 one of ventrads appearing simultaneously. Thus 

 in the corresponding inter-mesenterial spaces a 

 brace of new mesenteries appears, the order being 

 comparable even in detail to the order of appear- 

 ance of the septa in the Paleozoic Tetracoralla. 



A EEGTILAB meeting of the section was held at 

 the American Museum of Natural History, on 

 April 12, 1909. In the absence of Mr. Frank M. 

 Chapman, chairman of the section, Professor Chas. 

 L. Bristol presided. The following papers were 

 read: 

 Final Report on the Exploration of the Faydm 



in 1907: Professor Henky F. Osboen. 



In the absence of Professor Osborn, this report 

 was given by Mr. Walter Granger, of the Amer- 

 ican Museum of Natural History. The speaker 

 stated that the collection obtained by the expedi- 

 tion has been prepared and proves to contain 

 representatives of nearly all of the mammalian 

 forms known from this region, together with 

 several new genera and many species. Among the 

 new forms are rodents, recorded for the first time 



from these beds, and two peculiar small forms of 

 uncertain ordinal positions. The collection con- 

 tains many fine specimens of described species 

 which add much to the previous knowledge of 

 these interesting mammals. Itoubt was expressed 

 as to the relationships of the genus Megalohyrax 

 to the Hyracoidea and Mceritherium to the Pro- 

 boscidia. The speaker stated that the collection 

 of 1907 is being increased through the efi'orts of 

 a representative maintained in the Fayflm. 



By chart and slides the geology of the region 

 was illustrated, also the important topographic 

 features and the method employed in prospecting 

 and collecting the fossils. 



Studies on Tissue Growth: Dr. Chas. R. Stock- 



ARD. 



The Partulas of the Society Islands and the 



Problem of Isolation: Professor Henkt E. 



Ceampton. 



The speaker presented some of the general re- 

 sults obtained during investigations in 1906, 1907 

 and 1908, dealing with the variations and dis- 

 tribution of terrestrial snails of the genus Par- 

 tula, inhabiting the Society Islands. The geo- 

 graphical and physiographical conditions were 

 described. The islands of this group are volcanic 

 peaks of a partially submerged range; these peaks 

 occur sometimes in contact, as in the double island 

 01 Tahiti, while others have greater or lesser dis- 

 tances between them. It is, therefore, possible to 

 correlate the specific differences between the snails 

 of different cones with the geographical proximity 

 of the cones. As each island peak is furrowed 

 more or less regularly by valleys and as the snails 

 occur only in the moist bottomlands of these 

 valleys, it is possible to correlate the degree of 

 resemblance between the species of neighboring 

 valleys with the degree of geographical isolation. 

 In brief, such correlations are extraordinarily 

 close, as in the case of the classic Achatinellidse 

 of the Hawaiian Islands described by Gulick. 



The varieties of snails growing in different 

 valleys of one and the same island, or in different 

 islands of the group, can not be regarded as pro- 

 duced in different environmental circumstances. 

 Several illustrations were given which established 

 this conclusion. The phenomena of mutation were 

 observed in several islands. Finally the role of 

 natural selection was determined to be a much 

 restricted one in the case of these snails. 



L. Hussakof, 



Secretary 



American Museum of 

 Natural History 



