I0 CHHVUEROID FISHES AND THEIR DEVELOPMENT. 



second visit to the Californian coast during the summer of 1899. This visit resulted 

 in the taking of 179 female Chimaera, from which 20 eggs were secured. In addition 

 to the latter, a single egg containing a late embryo was obtained, which had become 

 attached (65 fathoms) to one of the hooks of a trawl line. It is upon these stages, 

 accordingly, that the writer has had to depend for his review of the development of 

 Chimsera. He may add that he was able to secure several notes regarding the 

 eggs of Chimcera phantasma and of Chimcera -mitsukurii during a stay in Japan, 

 and that he has further had the opportunity, thanks to his European colleagues, 

 of examining Chima^roid eggs and young in several museums, notably in Paris, 

 London, Berlin, Bergen, and Tromsoe. 



The present introduction would be seriously incomplete without reference to 

 the generous aid which has been given the writer at various stages of his work. 

 Especially helpful were the suggestions of Dr. Tarleton H. Bean and President 

 Jordan, and the many courtesies received from Professors Gilbert and Jenkins, 

 Directors of the Hopkins Laboratory, and from other members of the staff of Leland 

 Stanford University, notably Professor Wilbur. Grateful acknowledgment should 

 be made to Professor Theodore N. Gill, who very generously examined the proof 

 of the present paper. In Japan, also, while a guest of the Imperial University's 

 laboratories, both at Tokyo and Misaki, the writer acknowledges the valued aid 

 of Dean Mitsukuri and his associates. Finally, especial thanks are due to Dr. 

 Naohide Yatsu, Rigakushi, for his assistance both in Japan and in New York, 

 preparing many text-figures, and aiding notably in the section of the present 

 memoir dealing with the fertilization of the egg. During the latter study Mr. 

 Yatsu's comments, it need hardly be added, were especially valuable in view of 

 similar studies which he had undertaken in the case of invertebrates. 



The present memoir includes the following themes : 



I. Chimsra and its characteristics. Appearance, movements, sexual differences, feeding. 



II. Development: 



Breeding habits, mode of depositing eggs, and rate of embryonic development. 

 The capsule and its formation. 

 The egg and its membranes. 

 Fertilization. 

 Segmentation. 

 Gastrulation. 



Early embryos, i. <?, prior to appearance of gill-openings. 

 Late embryos, i.e., from appearance of gill-openings to time of hatching. 

 Immature 3 r oung. 



Morphology. Reference to: (a) integument and dentition; () skeleton; (f) viscera; 

 (tf) nervous system. 



III. Fossil Chimseroids and their significance in the study of recent forms. 



IV. Chimseroids in the problem of vertebrate descent. 

 V. Literature of Chimaeroids. 



