2 Prof. Allman on the Structure and Terminology of 



claim for their retention if any better be suggested, that I would 

 now defend them, but it is because, while admitting the force of 

 Prof. Huxley's criticism in some points, I feel that in others he 

 has not entirely understood my views, and that several of his 

 objections to my terms are founded on a misapprehension of the 

 sense in which I have used them. 



It is true that, since I first proposed a terminology of the 

 parts in question, increased opportunities of observation have 

 given me a clearer perception of the relations of these parts, and 

 have somewhat modified my original views j but I see no reason 

 to abandon the opinions 1 had expressed in some of my later 

 publications. 



I fear indeed that I have been occasionally somewhat obscure 

 in my definitions, and that the sense in which I wished to apply 

 certain terms has thus been not at all times sufficiently appa- 

 rent. The accompanying diagrams, however, will explain my 

 views of the structure of the parts under consideration, and, far 

 better than any mere description, will fix the meaning of my 

 terminology. 



Fig. I. Fig. 2. 



Plans of typical Gonophore. 1. Containing sporosac. 2. Containing 

 medusoid. The same kinds of shading and the same letters are adopted 

 in the two figures, with the view of indicating the homologous parts. 



a, ectotheca ; b, mesotheca or umbrella ; c, endotheca ; d, spadix ; 

 e, cavity of spadix ; c-\-d, manubrium ; /, generative elements ; g, radiating 

 canals ; h, marginal tentacle ; i, velum ; k, peduncle ; 7, ectoderm of cce- 

 nosarc ; m, endoderm of cccnosarc ; n, somatic cavity. 



The gonophores are certain buds of a peculiar structure, de- 

 stined for the formation and protection of the generative ele- 

 ments. 



