28 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. I40 



pods and are not easily identified. In silver preparations the matrix 

 of these entities is amorphous, but a few dark fibers are seen scattered 

 throughout it. 



It is generally accepted that this homogeneous ground substance is made of 

 innumerable fine, branching, arborizing fibers interwoven and matted together, 

 but . . . they are not visible as separate entities. (Power, 1946b, p. 488.) 



Another tract associated with the glomeruli of bipuncHceps may be 

 called the "olfactorio-globularis" tract. Hanstrom (1928) considered 

 this to be one of the most primitive tracts in the arthropod brain hav- 

 ing antecedents, perhaps, in the Annelida. Its presence may be ex- 

 pected, therefore, in the geophilomorph brain. Like so many fibers 

 in our preparations, those associated with this tract are extremely 

 difficult to follow. It is most probable, nevertheless, that some of the 

 fibers cross to the opposite side by way of a small commissure located 

 dorsoposteriorly in the protocerebrum (pi. 3, fig. 2, PB). 



There are no structures in the cephalic nervous system of bipuncH- 

 ceps which can be homologized with the "corpora pedunculata" or 

 with the "central complex" of the scutigeromorph and higher forms. 

 These components are well developed in the higher arthropods with 

 compound eyes, especially the social insects (Kenyon, 1896; Thomp- 

 son, 1913 ; Power, 1943) and are, in large part, fibrous entities. They 

 are poorly developed in the Lithobiomorpha and Scolopendromorpha 

 (Fahlander, 1938). In bipuncHceps the "pars intercerebralis" consists 

 of a cellular cortex and occupies the greater extent of the midline be- 

 tween the frontal and antennal lobes. The first anterior continuity 

 of the neuropile in the median plane occurs in the anterior half of the 

 tritocerebrum. This however, has already been identified as the sto- 

 matogastric bridge. A diffuse array of fibers which probably represent 

 a fusion of the anterior and posterior commissures of the deutocere- 

 brum (fig. 5, DC = ADC-fPDC) is dorsal to this bridge and slightly 

 caudal. Fibers run, it appears, in every direction. It is highly improb- 

 able, therefore, that either of these represent vestiges (or Anlagen!) 

 of the corpora pedunculata or central complex of the higher 

 arthropods. 



A commissure occurs between the frontal lobes about 40 micra 

 caudal to the stomatogastric bridge. It is dorsal and posterior to the 

 canalicular space containing the median cerebral vessel. This narrow 

 filet of fibers is considered to be the "protocerebral bridge" (pi. 3, 

 fig. 2). 



A large mass of commissural fibers is observed about 30 micra 

 caudal to the protocerebral bridge. Its dimensions are enormous in 

 contrast to the other commissures mentioned (pi. 4, figs. 1-3). Begin- 



