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ATl-RALIST [Vol. LIII 



as was previously stated, the trilobites do not stand in 

 the direct line of descent of the Leptostraca, and those 

 characters which they possess in common were inlierited 

 from their common l)ranchiopod ancestry, and can not 

 be interpreted as indicating that the trilobites represent 

 the ancestral forms .giving rise to the lepostracan type. 

 The fossil leptostracaii H f/iix Hnrdi is is evidently related 

 to the fossil branchiopod Wnj^iia (which occupies a posi- 

 tion intermediate l)etw(M'ii tlic binuchiopods and Lepto- 

 traca), but Ihiwrnnrmis i> rh.arly a loi)tostracan. and 

 resembles siidi li\iiig I'ornis a> Xchfilia. while tlic fossil 

 leptostracaus Cnmnrni/in and 'iniont rociiil)!*' siirli liv- 

 ing Leptostraca as Xrhalinpsis tiiptat in the character 

 of the cara])ace, etc. The closer affinities of the fossil 

 Ceratiocarid^e, etc., have not been determined, due to the 

 imperfect preservation of the limbs, etc., but they clearly 

 belong to the le])tostracan group. There is much to be 

 said in favor of incliidin- the Leptostraca in the next 

 groHi) of the Malaco>traca t<) lu- considered. Imt from the 



consider the Leptostraca (together with other primitive 

 forms not yet described) as nearer the ancestral forms 

 from which the other Malacostraca were derived. 



A fni-tliei- stage of development is represented by the 

 Anoinostraca-( 'uniacca group which includes the Synca- 

 rida and a i)(trtion of tlic Peracarida of Caiman's classi- 

 fication, together with their immediate relatives. The 

 Anomostraca ( Ana^pi<lacea and P.athynellacea of Thap- 

 pius, 1915), My.Mdacea and Cnniacea are very closely 

 interrelated and all of theni exhibit affimti.'s with the 

 Leptostraca, so that the member- of th<' h'ptostracan 

 group might well be includetl Iutc al<o; hnt the>- have 

 been treated as a separate ui'onp. to enipha->i/e the fact 

 that they occu])y a )»osition annectent hetwet'n the 



stron,u(-t' affinities hn-). ' Althon-li the nuMnbei-s .»f Ano- 



