NO. 4 NERVOUS SYSTEM OF A CENTIPEDE — LORENZO 35 



sure in question innervate the hypopharynx. Ferris disagreed re- 

 peatedly throughout his article with Fahlander's description of hypo- 

 pharyngeal innervation but added : "There are present a pair of 

 nerves . . . corresponding in position to Fahlander's n2o but which 

 innervate the muscles of the hypopharynx with a branch proceeding 

 laterally of the mouth opening." (P. 12.) Fahlander's n2o w the 

 tritocerebral commissure ! 



It at once becomes clear to one who has studied both articles that 

 the interpretation given by Ferris to Fahlander's descriptions do not 

 seem to be accurate. On the contrary, the reliability of Fahlander's 

 work has been enhanced by the study of the points of disagreement 

 uncovered by his antagonist. 



CONCLUDING COMMENTS 



The results of this paper do not allow broad speculation on the 

 problem of chilopod evolution ; general conclusions are impossible 

 without considering all the morphological features as a whole. This 

 research was initiated on the supposition that the nervous system of 

 the Geophilomorpha might furnish evidence conducive to a solution 

 of the problem of their disputed position on the chilopod tree. Some 

 authors have considered the scutigeromorph as primitive and the 

 geophilomorph as degenerative ; others have looked upon the modern 

 centipedes as offshoots of a geophiline stock. 



In the course of the study of the nervous system of hipuncticeps, 

 the relevant literature was consulted and it was found that in each 

 order of the class there is an admixture of features, some presumably 

 conservative, others theoretically highly derivative. The presence of 

 compound eyes in the scutigeromorph, the shape of the head capsule 

 and position of the antennae, the peculiar scape organ of the an- 

 tennae — found nowhere else among the centipedes — set this order 

 apart from the rest of the Chilopoda and closer to the higher insects. 

 The geophilomorph, on the other hand, with its absence of eyes and 

 of the Organs of Tomosvary, its homomeral condition and intraspe- 

 cific variation of the number of segments, manifests a simplicity only 

 vaguely hinted at in the Scolopendromorpha. It is indeed a difficult 

 task to answer the question: Which of the present-day chilopod 

 orders has the closest affinity to the primitive condition of the hypo- 

 thetical "Ur-Chilopoda" ? 



Homomerism and high and variable number of tergites have been 

 considered primitive characteristics ; the Geophilomorpha alone ap- 

 proximate this condition. Heteromerism with a low and fixed number 

 of tergites has also been called primitive ; the other three orders mani- 



