ASSORTIVE MATING IN CHROMODORIS ZEBRA 291 



single mass, while in December, with a sea temperature of 18°, 

 9 masses laid by individuals 9 to 12 cms. long contained on the 

 average 5,290 eggs (indicating a ''temperature coefficient (?)" 

 of about 1.6). The time required for the deposition of a mass 

 containing 4,000-6,000 eggs varies from 3 to 5| hours.' 



IX LITERATURE CITEDs 



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EiGENMANN, C. H. 1894 On the viviparous fishes of the Pacific coast of North 

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1910 The British nudibranchiata mollusca, Part VIII (Supplemen- 

 tary). Ray Soc, 1917 pp., 8 pis. 



Harris, J. A. 1912 a Assortive mating in man. Pop. Sci. Mo., May, p. 476-492. 



1912 b Pearl and Jennings on assortive conjugation in the Protozoa. 



[Review.] Science, N. S., vol. 35, p. 740, 741. 

 Heath, H. 1899 The development of Ischnochiton. Zool. Jahrb., Abt. Ontog., 



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^ Proof of this paper has been read by Dr. E. L. Mark. It has not beenpossi-. 

 ble to submit it to the author for his revision. — Editor. 



^ I am indebted to Prof. E. L. Mark for the use of separates of a number of 

 the articles consulted, and to Prof. H. S. Jennings for a copy of his paper, 1911 a. 



