32 



COLD SPRING HARBOR MONOGRAPHS. VIF. 



Foot No. 



Ramus, Outer or Inner. 



Outer Spines 

 Apical Spines 

 Apical Seta . . 

 Inner Setn; . . 



II 



III 



IV 



11 





 2 



^seta. ^1 large and 1 small. 



On all of the segments the outer margins of the rami are very 

 strongly spinous or hairy. 



The fifth foot is peculiar; the three characteristic "spines" grow- 

 ing right out of the posterior edge of the fifth thoracic segment. I 

 have been unable to detect any trace of a joint in the fifth foot of 

 C. phaleratus. The foot is outlined in camera drawings in Figs. 

 6 and 9, Plate XIV. A distinct transverse marking occurs below 

 the middle seta in Fig. 9, and this may indicate where a joint has 

 been; but the seta to the left grows directly out of the edge of 

 the fifth thoracic segment as does also the seta to the right. 



There is some variation in the spinous processes that occur on the 

 fifth feet, as can be seen by a comparison of Figs. 6 and 9, Plate 

 XIV. This difiference might easily be due to a difference in the 

 ages of the two forms represented. 



Forbes describes the fifth foot in C. phaleratus as consisting of 

 a flange-like projection more lateral than ventral, bearing the 

 characteristic armature. The Long Island form differs but little 

 in the shape of the fifth foot from Forbes' description, but shows a 

 distinct variation in the armature of this organ. 



Another variation is in the armature of the caudal stylets. The 

 apical structures in the Cold Spring Harbor form are strongly 

 serrated externally. On the inner surface they produce very small 

 hairs (Fig. 5, Plate XIV.). 



The posterior edge of the fifth thoracic segment is strongly 

 serrated ventrally as is likewise the posterior ventral edge of the 

 last abdominal segment. The spines are extremely coarse and pro- 

 ject over the caudal stylets. There is, in general, in C. phaleratus, 

 a strong tendency toward the production of spines. 



