36 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I40 



fest these characteristics. The compound faceted eye is regarded as 

 highly specialized by most entomologists, but some regard its presence 

 in the scutigeromorph as primitive. The absence of a visual apparatus 

 is degenerative or primitive depending on the taxonomic scheme one 

 favors. Anamorphosis and epimorphosis are simultaneously the 

 primitive postembryonic state! 



Are the simplicity of the geophil brain and the absence of photo- 

 conductor elements in the neuropile conservative or specialized? 

 Fahlander's aversion to more than one parallel evolution seems to be 

 the prime reason for his refusal to admit that the geophilomorph may 

 represent the primitive stock of the Chilopoda. Although his argu- 

 mentation is sound, it rests on an undemonstrated "principle of 

 economy" and is undoubtedly influenced by his selection of Verhoeff's 

 system of classification. The dismissal of difficulties of variation by 

 attributing them to "adaptations to a modus vivendi" seems to be 

 evading the issue. Evolutionary mechanisms are being better under- 

 stood today to make that line of argument more and more tenuous. 

 It is the author's hope that the neglected chilopods will receive more 

 attention in the future. Only then will the existing arguments about 

 their phylogeny be tested. 



VI. SUMMARY 



1. The anatomy of the cephalic nervous system of Arenophilus bi- 

 pimcticeps (Wood) was studied. Serial sections were prepared and 

 studied with trichrome and silver impregnation techniques. Graphical 

 reconstructions were made to demonstrate the more gross relation- 

 ships. Photographic methods aided in the interpretation of micro- 

 scopic relationships. 



2. The brain, or supraesophageal ganglion, is composed of a proto- 

 cerebrum, a deutocerebrum, and a tritocerebrum, which may be dis- 

 tinguished histologically. Grossly, however, they are fused into a 

 single mass. The brain is connected to a subesophageal ganglion by 

 long, cordlike circumesophageal connectives. Both ganglia are 

 composed of a cellular cortex and a fibrous core. The constituents are 

 bilaterally symmetrical in number and position. 



3. The cephalic nerves emerge from the three neuromeres of the 

 brain and subesophageal ganglion and are homologized with those 

 of other chilopods. A cerebral gland is associated with the frontal 

 lobes of the protocerebrum. The nerve to the gland exhibits possible 

 neurosecretory significance. Nerves supplying the intrinsic and ex- 

 trinsic musculature of the antennae were traced to their nuclei of 

 origin located ventrally in the deutocerebrum. The recurrent nerve 



