1892.] NEW-VORK MICROSCOPICAL SOCIETY. 103 



company. In the brackish water sent me by Mr. Helm I have 

 found this form standing beside the variety just referred to and 

 shown in Fig. 2, where, from the retiring, solitary creature, it is 

 becoming a social colony like so many others of its congeners. 



Of course it is not possible to imagine the cause that induced 

 the embryo of the original aspirant after colonial honors to cling 

 to the lorica of the parent and there produce a lorica of its own; 

 and what induced other embryos to follow suit is as obscure; but 

 each lorica with its enclosed animalcule represents a mature and 

 full-^rown embryo which, for some reason unknown, had not 

 wandered, as is the usual custom, to found a home at a distance. 

 It will be noticed that the appearance of the imperfectly formed 

 colony is sufficiently different from the original, fresh-water in- 

 dividual to set the investigator to thinking ; and while it would 

 scarcely in this condition be figured and described as a new 

 species, yet it is not unreasonable to suppose that it is on its 

 way to that end, and that at some time in the near future it will 

 merit a place in at least a provisional, working list of species. 

 In these transition forms the primary, original foot-stalk answers 

 for a support to the entire community, as it will probably con 

 tinue to do, but the individuals of the group will in time, and 

 perhaps in not a remote time, learn that they can obtain a bet- 

 ter and a more constant food supply by elongating a foot-stalk 

 from the posterior extremity of each constituent member. The 

 colony, now irregular and incomplete, will then be symmetrical 

 and regular in contour, as all similar colonies prefer to be, and 

 each member will have the same opportunity to get food as every 

 other one. Each individual of all such colonies is really inde- 

 pendent of all others in the community, and its food supply 

 depends upon its individual efforts. To have one or more 

 deprived of its necessary aliment would be to weaken it, and 

 to weaken its offspring so that the embryos would degenerate 

 rather than develop upward ; it would undergo degeneration 

 rather than evolutionary advance. 



The embryo that discovered there were advantages to be 

 obtained by clinging to the parent's lorica, and thus sparing itself 

 the trouble and the exhaustion of secreting a foot-stalk of its 

 own, seems to have transmitted, in even a very short time, the 

 new habit to its embryo, and these imperfect colonies are there- 



