1914.] NATURAL SCIENCES OF PHILADELPHIA. 55 



thoracic segments are not prominent. Both Herrick and Miss 

 Byrnes have obviously dra^vn their specimens under pressure, when, 

 as I have repeatedly observed, the thoracic outline is entirely changed. 

 Fig. 5, PI. IV, shows the form of cephalothorax in life. The third 

 segment is finely serrated along its entire posterior margin (fig. 10, 

 Pi. IV). These serrations often are slightly larger at the end of the 

 marginal row. The fourth thoracic segment bears, laterally, a short 

 row of minute but rather coarse "hairs" (fig. 11, PI. IV). On the 

 corresponding portions of the fifth segment there are present similar 

 short rows of coarse hairs, but on this segment they are much larger 

 (fig. 8, PI. IV). The entire cephalothorax is to the abdomen as 7 : 5. 

 Its length to its width is as 2 : 1. 



The abdomen is wide, the first segment being but a little narrower 

 than the fifth segment of the thorax. In my drawing of the living 

 animal (fig. 5, PL IV) the first abdominal segment is foreshortened 

 owing to the curve of the entire dorsal surface. This fact, taken 

 together with the short first antennae and the method of locomotion, 

 suggests a strong resemblance to members of the genus Caniho- 

 camptus. The first three abdominal segments are finely serrate on 

 their posterior margins. These serrations in the fourth segment, 

 instead of stopping at the sides of the anal opening, turn anteriorly 

 and extend a short distance along either side of this opening. There 

 are, furthermore, between the upturned portion of the posterior row 

 of serrations and the side of the anal opening, two very minute rows 

 of what Schmeil calls "button-like projections" (fig. 6, PI. IV). 

 Neither Herrick's nor Miss Byrnes' drawings give an accurate view 

 of this armature, though the former evidently noticed this detail 

 from his fig. 11, PI. 21, of his report of '95. Miss Byrnes' drawing 

 shows the marginal row of serrations of the fourth abdominal segment 

 extending across the anal opening. All the abdominal segments 

 bear transverse rows of minute indentations of the form of the 

 marginal serrations, but not projections of the cuticula. This may 

 easily be proved by turning the animal on its side, when the dorsal 

 and ventral lines of the abdominal segments will appear as unbroken 

 lines. I find this character quite constant in specimens of the 

 variety poppei, though Schmeil notes that it is often missing in the 

 type jimbriatus. 



The stylets (fig. 6, PI. IV) differ from those of the typical ^w6na^MS. 

 They are only as long as the last two abdominal segments. Their 

 length is three times their width and their inner margins almost meet 

 at the point of insertion in the abdomen. One of the main differences 



