258 Miscellaneous. 



masked the true affinities in the eyes of naturalists. It is among 

 the Rotifera that we must seek the origins of the three groups ; the 

 Gastrotricha lead to the Annelida through the genus Hemldasys *. 

 .... The affinities of the embryos of the Gasteropoda with those 

 of the Rotifera {Brachionus) have already been brought to light by 

 the fine investigations of Salensky." 



Somewhat later f the author maintained that the perfect agree- 

 ment furnished by the superposition of the first embryonic stages 

 and the general presence of the Trochosph e ra-stage in the Mollusca, 

 Polychoetous Annelida, Rotifera, Brachiopoda, and Bryozoa show 

 clearly that these various groups belong to a single mass. To the 

 objection that the embryogeny of the Oligochaeta, Hirudinea, Cepha- 

 lopoda, and Nematoda presents considerable differences from that 

 of the above types, he replies that these groups are so united to the 

 preceding ones by a series of forms allied anatomically and organo- 

 genetically that we must regard them as the extremities of those 

 branching series of which Lamarck indicated the existence in the 

 heart of his fundamental masses. Some of them perhaps (Nema- 

 toda, Oligochseta) diverged from the common stem before the Tro- 

 chosphvera-stage. External form may be misleading — there is more 

 difference between an Ascaris and a Serpula than between a Ser- 

 pula and a Terebratula. From the anatomical conformity between 

 the Oligochaeta and the Polychaeta it would seem that, at least in 

 this case, there has simply been falsification of the embryogeny in 

 the former. As Euacses and Lumbricus issue from the ovum nearly 

 in the adult form, the TrochospJuera-sUige has been suppressed. In 

 Limnceus the embryo leads a half-free life in the liquid which sur- 

 rounds it, and we find a Trochosphere reduced in proportion to the 

 freedom of movement. 



In 1878 X the author insisted agaiu upon the necessity of creating 

 for the Mollusca, Annelida, and satellitic groups, a group equivalent 

 to the Vertebrata and Arthropoda, for which he proposed the name 

 of Gymnotoca. It was characterized anatomically by the existence 

 of a secondary excretory system (deutonephra or segmental organs) 

 replacing the primary excretory system (protonephric system), the 

 existence of which is permanent in the ancestral group of the Platy- 

 elmintha. The phylum Gymnotoca was divided as follows : — 



(1. Mollusca: Cephalopoda, Gasteropoda, Acephala, 

 Scaphopcda, Polyplacophora, and Neomenida. 

 fi-viwvrrvrnri a J %• Annelida : Chsetopoda, Gymnotoma (Polygordius), 

 OYMJNU1 UUA s, Hirudinea, Gephyrea, Chtetognatha, &c. " 



| 3. Beachiopoda. 



14. Ciliata : Rotifera, Gasterotricha, Bryozoa. 



* M. Giard now regards Dinophilus as more ancestral, but this is only 

 of secondary importance here. 



t ' Revue Scientifioue,' March 18, 1876, p. 277, 

 \ Bull. Sei. du Nurd, 1878, pp. 47 et seqq. 



