ZOOLOGY 389 



Other papers include : 



Dickey, " A New Amphibian Cestode " {Journ.Parasit., vol. vii, March 1921); 

 Schwarz, "A Microsporidian occurring in the Smelt" [ibid., March 1921) ; 

 Starr, " Effects of Variations in Oxygen Tension on the Toxity of Sodium 

 Chloride " [Biol. Bull., vol. v, pt. 40, Nos. 9, 3, March 1921) ; and Ward, 

 " A New Blood Fluke from Turtles " {Journ. Parasit., vol. vii, March 1921). 



** Studies of the Development and Larval Forms of Echino- 

 derms " {Gad Copenhagen, 192 1 ) is the title of a paper by Morte- 

 sen. This volume of 261 pages and 33 plates constitutes a 

 fairly full treatment of the larval echinoderms investigated 

 when fresh as the result of two years' travelling and collecting 

 in various parts of the world, particularly the Pacific region. 

 While not belittling the work that has been done on the hybri- 

 disation of echinoderms, the author calls attention to the fact 

 that with a few exceptions it has not been of an entirely satis- 

 factory nature, partly because of our fragmentary knowledge of 

 these forms and partly because until recently the hybrids have 

 never been reared far enough. The present work has gone a 

 long way towards providing a satisfactory book of reference of 

 normal forms, the knowledge of which should undoubtedly 

 precede work on abnormal ones, and it will no doubt form the 

 basis of future work along these lines. 



In addition to a well-illustrated and detailed description of 

 about 80 species and their metamorphosis there is also an 

 introduction, a discussion of their classification, morphology, 

 phylogeny, biology, and geographical distribution. 



Other papers include : 



Lillie, " Studies of Fertilisation. VIII. On the Measure of Specificity 

 in Fertilisation between two Associated Species of the Sea-urchin, Genus 

 Strongylocentrotus; and IX. On the Question of Superposition of Fertilisation 

 on Parthenogenesis in Strongylocentrotus purpuratus " (both in Biol. Bull., 

 vol. 40, No. I, Jan. 192 1) ; and Newman, " On the Development of the Spon- 

 taneously Parthenogenetic Eggs of Asterina {Patiria) miniata," and " On the 

 Occurrence of Paired Madreporic Pores and Pore Canals in the Advanced 

 Bipennaria Larvae of Asterina [Patiria) miniata ; together with the Discussion 

 of the Significance of Similar Structures in other Echinoderm Larvae " (both in 

 Biol. Bull., vol. 40, No. 2, Feb. 192 1). 



O'Donoghue has provided a list of the " Nudibranchiate 

 Mollusca from the Vancouver Island Region " {Trans. Roy. 

 Canad. Inst., vol. xiii, No. i, 192 1). This contains an ac- 

 count of the diagnostic characters, structure of the radula and 

 the distribution of 26 species, 8 of which are new. It is based 

 on the examination and collection of a large series of specimens 

 and helps to fill in the gap in our knowledge of the Nudibranchs 

 of the Pacific coast of North America since the previous collect- 

 ing had been done in Alaska or in California. 



