The Craspedosomatidae of North America. IT 



II. — A Possible Auditory Organ. 



Between the base of the antenna and the neighboring ocelli is 

 a ring-like elevation of the chitinous surface of the head. We 

 have been able to find this in most of the diplopod families. In 

 the Craspedosomatidae it is well-developed, — nearly as large as a 

 single ocellus. Sometimes it appears that the surface included 

 in the ring is covered by a delicate membrane, at others the ap- 

 pearance is that of a dark central spot or aperture (fig. 133). 



That the structure in question is a sense-organ appears ver}'' 

 likely, but its function can only be conjectured. It is not impos- 

 sible that it may prove to be an auditory organ. Certain species 

 of Glomeridse, of the genus Sphserotherium are known to have 

 stridulating organs, and in them, at least, an organ of hearing 

 would be expected. That other diplopods stridulate is not 

 known, and would seem unlikely. There have been also no experi- 

 ments to determine whether they are able to hear, and such ex- 

 periments would be \evy difficult and probably unsatisfactor3\ 



III. — The Lahral Hairs. 



On the labrum is a transvere row of long hairs provided in 

 some forms, at least, with neural connections (fig. 194). These 

 hairs do not appear to be especially diff'erentiated in structure. 

 They are placed in depressions, though this is not so much the 

 case in the present family as in the lulidse. The best guess 

 would probabljr be that they have merely tactile function. The 

 number and arrangement of the hairs is very constant. 



lY. — Gnathochilarium. 



1. Cones similar to those of the Antennse. — On the apices of the 

 processes of the stipes, and on the lingual lobes are more or less 

 numerous conical structures resembling in a general way the so- 

 called olfactory cones of the antennae (fig. 59). The fibrillated 

 structure is still more apparent than in those organs, and the 

 neural connections are very evident. They are also much shorter 

 and proportionally broader than the antennal cones, have 

 thicker walls, and a more evidently' hollow apex, the wall there 

 being exceedingly thin. The size is very variable. 



There is no inherent improbability in the idea that these are 



Annals N. Y. Acad. Sci., IX, Oct., 1895—2 



