Xo. 625] THE EVOLUTIOX OF ARTHROPODS 



169 



parison with the multitude of resemblances between in- 

 sects and their real ancestral forms), it may be said that 

 these same structures are likewise shared by such fossil 

 merostomes as Bunodes himda and on precisely the same 

 ,s:rounds, insects should be derived from merostomes also 

 (a manifest impossibility) since those have tlie same 

 ancestral qualifications of urcat antiquity, and they 

 possess the Irilohite tspe ol' aii1eiiii:e. rxc^ .-iiid l.-iteral 

 tergal projections! AVlieii one studies tiie eiiibryolooical 

 development of in>eet-, however, it i- e\i(U')it that their 

 ancestors iiad tiro i^airs of antenna^ instead of the one 

 pair apparent in trilobites, and the insectan type of head 

 is nothing- like that of a trilobite in which the head region 

 is not set off by a marked constriction witli well-defined 

 mandibles, maxilhi^ and underlip of tlie insectan tyj)e. 

 while the head region and mouth parts of isopod and 

 ampliipod (.'rustacea, etc. (with their two pair of aii- 

 tennip, insectan type of head, mandibles, maxilhr and 

 underlip), are clearly similar in character to wliat the 

 ancestors of insect'; mu<t have lieen like, and the ^ame 

 ]h)1(1> true of the leg^ nud terminal ap])endage^, etc., in 

 these Crustacea. TlKTci'tn'e. far a> (•()m|)arative 

 aiuitomy is concerned tlu' ( rn-1aee;i. with their progeny 

 the Symphyla. etc., are, heyond any p()s>il)irity of doubt, 

 the nearest forms to the ancestors of in.^ect^ in general, 

 and this is also borne out by embryology, which, how- 

 over, can not be ai)i)lied in the case of the trilobites; so 

 that here we must depend largel\- upon comparative 

 anatomy, whose verdict is unmistakably in favor of the 

 Crustacea, Symi)hyla and Apteiyuota as tlie ancestral 

 forms leading uj) to the ptei-yuotau type, junl is uimiistak- 

 ably against eonsidei'iim' the irilohite^ anywliere near the 

 immediate ance-tor- ol' wiimcd in-eets or oxon in their 

 direct line (d' de-cent. ()n tln> account, it is most 



Knedcmaun. liMC). Lull. l!M7. dc. ) huw accepted with- 

 out r,-,.r\atinti ^uch <tartlinul\ r.'x -dut ionar) id^:,. 

 those propcM'd hy llandlirM'li- and upon Mtdi nu-aiivrly 

 insufhcient grounds when one looks into the subject at 



