^ 



xcvi GENERAL SUMMARY OF SCIENTIFIC AND 



fossil remains of them are found in the lowest Silurian forma- 

 tions) were developed from the Hydroid polyps by transmuta- 

 tion. " We have in the Rhahdopleura manifestly such a form 

 of Polyzoa in course of development out of a form of Hydro- 

 zoa." Finally he calls attention to the interesting fact that 

 the crown of tentacles of this animal is like that of most 

 fresh-water Polyzoa, and in this respect is higher than the 

 marine forms. " It is, however, possible," he says, " that the 

 first is pi'operly the original form, from which the latter has 

 subsequently arisen." The fresh waters appear, as Haeckel 

 lately has remarked, to contain the direct descendants of some 

 of the eldest animal forms which, by reason of the less compli- 

 cated accidents of the fresh waters, have often in the "struQ-- 

 gle for life" only slightly altered their original more simple 

 structure ; as, for instance, among the Coelenterates, the Hy- 

 dra; among the Rhizoj^ods, the Actinophrys^ Grotnia., and 

 the shell-less Hadiolaria lately discovered by Focke ; among 

 the fish, the Ganoida^ etc. The dee23-sea Polyzoa dredged 

 by Pourtales ofi" Florida have been described by Professor 

 Smitt in the Swedish Transactions. 



Turning now to Professor Morse's work on the "Systemat- 

 ic Position of the Brachiopods," we meet with the iconoclas- 

 tic statement that " the Brachiopoda are true worms, with 

 possibly some affinities to the Crustacea, and that they have 

 no relations to the Mollusca, save what many other worms 

 may possess in common wdth them." He not only regards 

 them as worms, but as belonging to the highest division of 

 them, the Chsetopods, represented by the marine forms, such 

 as JVereis, Amphitrite, Sabella, and less perfectly by the com- 

 mon earthworm. He regards the Brachiopods as a synthetic 

 or comprehensive type, saying that " w^hile we do not find 

 them in all their characters resembling any one grouj:* of 

 worms, I have endeavored to show that all their features, to 

 a greater or less degree, are shared by one or the other of 

 the various groups of the Vermes, with one or two features 

 shared by the Arthropods." In his belief the ancient Chteto- 

 pod worms culminated in two parallel lines, on the one hand 

 in the Brachiopods, and on the other in the fixed and liighly 

 cephalized Chaetopods. The divergence of the Brachiopods 

 having been attained in more ancient times, a few degraded 

 features are yet retained, whose relationships we find in the 



