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A Contribution to the Life-History of Botrylloides. 



By T. Charters White, M.R.C.S., &o. 



(Read April 27th, 1877.) 



Plate XXVIII. — Lower Part. 



To treat of the Natural History of the whole of that division of 

 the Mollusca known as the Tunicata, with the fullness its interesting 

 character deserves, would be impossible in the limits of a short 

 paper, or within the time allotted to me ; but the members of this 

 Club, who are doubtless well informed of the characteristics of this 

 class, will perhaps allow me to call their attention for a few moments 

 to some particular observations I have been enabled to make, and 

 which I beg to offer as a contribution to the life-history of one 

 species, viz., Botrylloides. 



It was in the early part of the year 1876, that I discovered in my 

 aquarium a patch of Botryllus on some Ulva latissima, and wishing 

 to examine it more conveniently, I brought the Ulva close to the 

 front glass, and allowed it to remain there. After a few weeks I 

 observed that one corner of this patch had become attached to the 

 glass, and my interest was the more increased, since the fact of the 

 possession of locomotive powers in this class of the Mollusca had 

 not been noted by previous observers, except in their young and 

 larval condition, and I watched more closely than before to determine 

 if it really moved, or if it increased by subsequent development, and 

 could so reach the glass, and to my gratification I found that, while 

 it came more on to the glass, it retained its original size, an obser- 

 vation which, after some two months, was confirmed by the patch 

 having transferred itself entirely to the glass front of the aquarium, 

 where I hoped to be able to investigate its mode of progression as 

 well as the general economy of its life-history ; but owing to the 

 thickness of the glass, the imperfect illumination of the object, and 

 the want of transparency of the gelatinous mass in which the 

 zooids were imbedded, very little could be made out in its then con- 

 dition, but the following observations were readily noted : — The mass 



