No. 3] LOXOSOMA DAVENPORTI. 371 



number much too great to be explained as a chance variation. 

 My observations seem to show that they are more abundant 

 during the breeding season (July and August) than earlier in 

 the summer. That they are not the result of insufficient 

 nutrition, due to the development at the same time of sexual 

 products, is shown by the fact that the same parent frequently 

 bears a number of other buds all perfect and normal. 



The most reasonable explanation of these abnormal buds, in 

 view of all the facts observed, is suggested by comparing 

 these with specialized individuals of a colony, the avicularia or 

 vibracula of certain Ectoprocta. If Loxosoma be assumed to 

 be derived from stock-building ancestors, the imperfect buds 

 may be readily explained as manifestations of the tendency — 

 not yet eliminated — to produce similarly modified individuals. 

 This I regard as probably the correct view, though it is con- 

 trary to the one generally accepted, according to which Lox- 

 osoma is regarded as a primitive form which branched off from 

 the main stem of the Endoprocta before the colonial habit 

 of life was acquired. It seems to me more probable that 

 Loxosoma has secondarily abandoned the colonial habit in 

 adaptation to the commensal or parasitical mode of life. 



The number and size of the buds found attached to a parent 

 suggest that this species comes nearer perhaps to the formation 

 of stocks than any of the species of Loxosoma which have been 

 described heretofore. 



Excretory Organs. — Two forms of excretory organs have 

 been reported for the genus Loxosoma. That described by 

 Harmer ('85) was essentially an intracellular tubule terminated 

 by a flame cell and resembling in all important characteristics 

 the excretory organs of flatworms, annelid larvae, rotifers, and 

 several other genera of Endoprocta (Pedicellina, Urnatella, etc). 

 The other form of excretory organ is that described by Prouho 

 ('91) for L. annelidicola. In this case the ciliated canal to the 

 exterior could be seen in the living animal, but its internal end- 

 ing could not be made out clearly. However, the author could 

 get no evidence that the tube ended blindly (en cnl-de-sac). 

 Near the inner end of the tubule was a group of two or three 

 very large cells filled with yellowish granules. The cells were 



