400 SCIENCE PROGRESS 



a description of new members of the genus Philliinse, it also 

 includes a useful discussion of their relationships with other 

 Actiniiae, in which a decidedly novel method of dealing with 

 the question of the systematic position of animals is put for- 

 ward. It is suggested that certain characters in these forms, 

 e.g. the presence or absence of a mesoglceal sphincter or of 

 acontia, etc., should be regarded as " unit characters," and 

 that they " have all the properties of, and may legitimately be 

 identified with, Mendelian units." Having made this assump- 

 tion the author has "... endeavoured ... to arrange certain 

 limited morphological and systematic data in conformity with 

 the conclusions reached by the Mendelian school of zoologists, 

 and indicated a method that seems to me appropriate to the 

 purpose. In so doing I am aware that I am proposing a 

 revolution in our methods of envisaging and dealing with 

 morphological and systematic problems." Whether the 

 author's premises will be accepted or his method widely 

 adopted the future must decide, but they are obviously points 

 that need to be considered by the systematist. 



Other papers include : Hargitt, " Germ Cells of Ccelenter- 

 ates. 5. Eudendrium ramosurn " (Jour. Morph. vol. xxxi, 

 June 191 8) ; Walton, " Longitudinal Fission in Actinia bermu- 

 densis Verrill " (ibid.). 



Essenberg has discussed " The Factors controlling the Dis- 

 tribution of the Polynoidae of the Pacific Coast of North 

 America " (Univ. Cat. Pub. Zool. March 191 8). In this a 

 review is given of the known facts concerning the distribution 

 of the fifty-three species of Polynoidae occurring on this area : 

 some are cosmopolitan, but others restricted to the Pacific Coast 

 and even to small areas of it. The most important determining 

 factors were found to be temperature, currents, winds, chemical 

 composition of the water, food, habits and mode of life, and 

 the plasticity of the animal itself. The greatest number of 

 Polynoids are to be found in the Littoral zone. In view of this 

 and the fact that they are more uniform there than at greater 

 depths, the author suggests that the Littoral zone is at any 

 rate the centre of dispersal and perhaps the centre of origin 

 of the group. 



Other papers include : Kepner and Rich, " Reactions of the 

 Proboscis of Planaria albissima Vejdovsky " (Jour. Exp. Zool. 

 vol. xxvi. May 191 8). 



