34 



BULLETIN 54, UNITED STATES NATIONAL MUSEUM. 



" The chelaB are short and very stout; the second joint is particularly 

 stout, as compared with the others; the third joint as usual is very small, 

 a portion of the fourth coming to articulate directly with the second; in 

 the fifth joint the palm is straight for the first half, the margin being 



fringed with fine, closely-set den- 

 ticles; the distal half is furnished 

 with blunt tooth-like processes, 

 and is bent downward at an oblique 

 angle; it terminates in a short 

 pointed extremity which is bent 

 upward; toward the distal extrem- 

 ity are a few slender hairs scat- 

 tered here and there; the finger 

 gradually narrows toward its ter- 

 mination in a curved pointed ex- 

 tremity; the inner margin is pro- 

 vided with a number of low tooth- 

 like processes, each terminating 

 in a sharp point which is directed 

 forward. 



"The remaining thoracic limbs 

 are more or less similar to each 

 other; there is no difference in 

 size between the anterior and 

 posterior series, but a slight differ- 

 ence in structure; the proximal 

 joint is very long, the second ex- 

 tremely short; the third is about 

 half the length of the proximal 

 joint, the fourth and fifth are 

 rather shorter and subequal; the 

 terminal joint of the limb has the 

 form of a long slender spine; the 

 inner margin of the penultimate 

 joint has a row of stout spines, 

 of which the distal one or two are 

 serrate; on the opposite side of the 

 joint are a number of more slender 

 hair-like spines; the antipenulti- 

 mate joint has a similar structure, 

 but the spines are not so strong; 

 the distal joints are nearly smooth, having only a very few slender 

 hairs developed at the point of articulation with the succeeding joints. 

 The above description applies to the first three pairs of ambulatory 

 limbs. The fourth, fifth, and sixth pairs of thoracic appendages 

 differ slightly in their structure from the anterior pairs; this differ- 



FIG. 32. NEOTANAIS AMERICANUS (AFTER BED- 

 DARD). a, SECOND ANTENNA. 6, GENERAL 

 FIGURE. 



