502 Illinois State Laboratory of Natural History. 



last papilla of the series is on XXII a 3 and is displaced 

 slightly mesiad. 



On somites XXIII to XXVI the carina? are absent and are 

 replaced by four pairs of large papilla?. These form two 

 short series which if continued forward would pass midway 

 between the median and lateral carina?. The first pair, 

 situated on the larger annulus of XXIII, is the largest, the 

 next somewhat smaller, while the others diminish rapidly 

 and converge posteriorly. Very minute papilla? may occur 

 on the preanal somite. 



All of the papilla? enumerated are of prominent conical 

 form, sharp-pointed, and high. Their summits bear a con- 

 tractile apex, which in some cases is almost filiform in exten- 

 sion, in others short truncate in contraction. Around the 

 base of this appendage a few smaller points may be clustered. 



In addition to those more prominent papilla? which have 

 been described, a more or less complete irregular series of 

 small papilla? forms a dorso-marginal line, external to which 

 a few are scattered along the margin and a still smaller 

 number on the internal side. None of these are ever elevated 

 on a ridge. 



The metameric sensilla? have the following positions (PI. 

 XLIL, Fig. 5 ). The dorso-medians (md) are just a little way to 

 the mesial side of the middle of the area between the median 

 and the dorso-lateral carina?, and are quite easily traced as 

 far forward as II. A curious* circumstance which requires 

 investigation is that a pair appears to lie on the integument 

 directly above the eyes. In the middle body region the 

 papilla? of this series are slightly elevated and they are every- 

 where the most conspicuous. The dorso-lateral sensilla 1 (dl) 

 are almost as evident on the head as the dorso-median, but 

 much less so on most of the body somites. They are just 

 external to the large papilla? of the dorso-lateral series, but 

 after the suppression of their guardian .papilla^, on XXIII, 

 they stand out much more prominently in their isolation. 

 The dorso-marginals (dm) become visible on III and continue 



♦Inasmuch as the eyes seem to be the representatives of the dorso-median sensitise 

 of somite III and to have undergone no shifting. 



