394 PROCEEDINGS OF THE ACADEMY OF [May, 



and gently enlarged toward the proximal end. Surrounding it is the 

 cuticular penis sheath, which is 12 or 13 times as long as its proximal 

 diameter and closely envelopes the penis except at the distal end, 

 where it expands broadly like the mouth of a trumpet. The epithelial 

 penis sheath (<?s.) expands distally into a bursa divided by a horizontal, 

 diaphragm-like partition into a larger dorsal chamber (dc.) which re- 

 ceives the free end of the penis and its cuticular sheath and a very 

 shallow ventral chamber (vc.) lined by enlarged cells. From this lower 

 chamber a narrow passage leads to the exterior. The entire penial 

 apparatus is ensheathed in muscle, for the most part arranged in two 

 layers, wound spirally in opposite directions and united at the proximal 

 end in a loose coil around the lower end of the vas deferens. Distally 

 these muscles partly unwind and form a sheet enveloping the bursa 

 and binding the entire organ to the body floor. 



Spermathecse (fig. 22) open as usual in line with the ventral setse of 

 X. They are usually bent into a coil and have a large spherical pouch 

 and a duct about twice as long, the proximal half of which is narrow 

 and the distal half expanded into a somewhat fusiform enlargement 

 with thick walls. 



This species occurs in considerable numbers along with Tuhijex 



hamatus under stones at half-tide on the Acushnet river, above New 



Bedford, Massachusetts. At flood-tide the water is here strongly 



brackish, and this species is of interest as the first of its genus to be 



recorded as occurring under such conditions, all other species being 



inhabitants of fresh water strictly. 



Enchytraeus albidus Henle. 



Enchytrceus albidus Henle, 1S37. 

 Halodrillus littoraUs Verrill, 1873. 

 Enchytrceus humicultor Vejdovsky, 1879. 

 Enchytraeus littoralis (Verrill) Smith, 1895. 



This, the best known and most generally distributed of our littoral 

 Oligochseta, was redescribed and identified with E. humicultor Vejd. by 

 Smith. Michaelsen, to whose monograph reference is made for the 

 complete synonymy, considers the latter to be part of E. albidus Henle. 

 It is an abundant species from Casco Bay, Maine, to Sea Isle City, 

 New Jersey, at least, and, while found more or less everywhere in the 

 upper littoral zone, is especially abundant in the windrow of eel grass 

 which traces the line of high-water along the beach. Wlierever the 

 eel grass is kept moist by brackish water and retains a thick coating 

 of diatoms to serve as food, these worms become large and stout, 

 attaining an inch in length and a millimeter in diameter. Elsewhere 

 they are smaller. The same species, but of smaller size, is found in 



