THE DEVELOPMENT 0$ ASTERINA GrSBOSA. 221 



The Development of Asterina gibbosa.^ 



By 



E. W. MacBi'idc, 



Fellow of St. John's College ; Demonstrator in Animal Morphology in the 

 University of Cambridge. 



With Plates XI— XXII. 



The investigations which form the subject of the present 

 memoir were commenced with the object of seeking in Asterids 

 the results which the author (14) had already obtained from the 

 study of OphiuridSj viz, the development of the so-called heart 

 and its accompanying sinuses. 



A study of the literature soon led to the conclusion that our 

 knowledge of the development of most organs in the Asterid body 

 was very defective, and that a thorough revision of the whole 

 embryonic and larval history would be most desirable. This 

 work has occupied my attention for the last two years^ and I 

 am now in a position to give a fairly complete account of the 

 whole organogeny; an account which will, I hope, place our 

 knowledge of Asterid development on the same level as that 

 to which our acquaintance with Crinoid ontogeny has been 

 raised by the researches of Bury (1) and Seeliger (18) ; I have 

 to express my warm thanks to Mr. Sedgwick not only for the 

 suggestion of Asterina gibbosa as a proper type to investi- 

 gate, but also for much assistance and advice in revising the 

 proofs of this paper. 



That there was an immense lacuna in our knoAvledge to be 



' A preliminary account of the observations recorded in this paper was the 

 subject of the successful essay in the competition for the Walsingham Medal 

 of the University of Cambridge in ] 893. 



vor,. 6. B 



