02'I Rev. T. Hincks on British Polyzoa. 



laid down, the cliief -weight will be assigned to zoooecial 

 affinity ; but cardinal and striking differences in the colonial 

 organization may require the separation (as a matter of clas- 

 sification) of forms agreeing more or less in the character of 

 the cell. I will give one or two illustrations. The Gemel- 

 lipora eburneay Smitt, forms erect shoots in its adult state, 

 and has its ivory-coloured cells, bearing a general resemblance 

 to those of Eucratea, arranged in pairs, back to back, like 

 those of Gemellaria^ but with a difference. The aperture is 

 nearly round, with a broad sinus below and two small lateral 

 sinuses. The Oemellipora striatula, Smitt, which is iden- 

 tical with Lepralia veiiusta, Norman, is an incrusting species, 

 its cells decumbent and adnate, arranged side by side, so 

 as to form a continuous expansion, and presenting in almost 

 every point a very marked contrast to G. ehurnea. But 

 there is a resemblance in the form of the aperture ; and on the 

 strength of this Smitt refers the two to the same genus*. In 

 this case, the shape of the mouth only is taken into account, 

 to the exclusion of the other portions of the cell, and the 

 colonial characters are of course entirely ignored. It can 

 hardly be contended that this is a natural alliance in any true 

 sense of the terra. It seems to me eminently unnatural; but 

 it is only one of many similar results to which the rigorous 

 application of Prof. Smitt's method has conducted him. 



To take another case. The Memhranipora vulnerata, Busk, 

 is a crustaceous form, spreading in patches of indefinite shape 

 and size, having the front area of its cells completely covered 

 in by a calcareous lamina, and furnished with vibracular cells, 

 which alternate with the ordinary zoooecia throughout the 

 colonyf. In the general character of the cells and the position 

 of the vibracula it agrees with the genus Cupularia^ Lamx. ; 

 but the latter possesses a zoooecium of definite form, usually 

 more or less conical or cup-shaped, and is free^ in all proba- 

 bility, in all stages of its existence, certainly in its adult state. 

 In recent specimens " the entire surface of both the concave 

 and convex surfaces is covered with a continuous chitinous 

 epidermis " [Busk]. 



Smitt unites M. vulnerata with GupulariaX, relying on the 

 general similarity of the cells and vibracula, and ignoring alto- 

 gether the remarkable difference in the organization of the 

 colonies, and the complete change which has taken place 

 in the conditions of the colonial life. I cannot recoa'nize 



* ' Floridan Bryozoa,' part ii. pp. 35, 37. 



t In another "part of this paper I have coustitnted a new genus for the 

 reception of this form, which is clearly distinct from Memhrampura. 

 X ' Floridan Brvozoa." part ii. p. 14. 



