% 



XEW NORTH AMERICAN EARTHWORMS 169 



External characters. — ^When collected the specimens apparently 

 had their length much decreased by strong contraction, with a re- 

 sulting increase in the diameter. The length of the preserved speci- 

 mens is probably not much more than half of that which they might 

 sometimes have had when crawling about under normal conditions. 

 The type specimen is about 105 mm long, the maximum diameter is 

 about 8 mm in the region of the eighth somite, and the average 

 diameter is about 6 mm. The average length of eight specimens is 

 101 mm, with extremes of 95 and 110 mm. The average maximum 

 diameter of the eight specimens is 7.8 mm, and the average of the 

 average diameters is 5.6 mm. The diameter midway of the length 

 of the clitellar region is less than elsewhere and is 4.5 mm in the type, 

 and 4.8 mm is the average in the eight specimens. The number of 

 somites is 202 in the type, and in eight specimens the average num- 

 ber is 200, with extremes of 186 and 217. 



The setae of the anterior region are located with difficulty be- 

 cause of their small size. They have a length of about 0.5 mm or less 

 and a diameter of 0.04 mm or less. The surface of the distal part 

 is but slightly sculptured and is nearly as smooth as that of the 

 proximal part. The setae are noticeably lacking in a few anterior 

 somites. In the part of the type specimen that was sectioned the 

 setae a were present only in somites 3, 5, and 10; setae 6 in 5, 7, and 

 10; and setae c and d were lacking in 1-10. There were somewhat 

 fewer setae lacking in other sectioned specimens. Setal sacs were 

 present in normal positions where setae were lacking. The penial 

 setae (« and & of 18) are very different in size and form from the ordi- 

 nary setae. Each of the two pairs is in a depression, and the setae 

 protrude from the wall a distance of 1 mm or more in most specimens. 

 Each of the penial setae examined is somewhat over 2 mm in length 

 and but slightly curved except near the outer end, where there is a 

 decrease in diameter and a rather abrupt curve, with the terminal 

 part at nearly a right angle with the main part and directed ante- 

 riad. The terminal part including the strongly curved part has 

 rather fine sculpturing, but the greater part of each seta is smooth- 

 surfaced and approximately 0.07 mm in diameter in the largest speci- 

 men and somewhat less in a smaller specimen. The spacing of the 

 setae is somewhat variable and in the anterior part of the worm is 

 approximately «« : «& : 6c : C(i= 10 : 2 : 7 : 4 ; del '\^ about three-fifths of 

 the circumference. 



The prostomium is small and prolobic. The first six somites are 

 biannulate or partially triannulate, and the following ones are defi- 

 nitely triannulate. The clitellum includes somites 13-19 and in one 

 specimen encroaches somewhat on 20. It is incomplete on the 

 median ventral surface. In some specimens it is somewhat tan- 



