356 THE ANNELIDA POLYCHAETA. 



region {i.e., near sixteenth somite) being sixteen times as wide as long. The 

 anus is terminal and is surrounded by a ring of tubercles; cirri on the ventral 

 side as very short subcorneal processes. 



The parapodia throughout the length of the body are located high on the 

 sides, near the dorsal level. All the parapodia are distinctly biramous, with the 

 branches well separated. The parapodia vary somewhat in form in different 

 regions. In the anterior region each branch consists of a low, rounded setig- 

 erous eminence with a conspicuous postsetal process. The postsetal process 

 of the notopodium is subcorneal, more or less flattened in the anteroposterior 

 direction and longitudinally furrowed or concave at base on the setal side; the 

 tip is prolonged and acute. The postsetal process of the neuropodium is similar 

 to that of the notopodium, but is shorter, broader at the base, being prolonged 

 at the base on the ventral side, and is rather more strongly flattened. (Plate 

 65, fig. 3). In the posterior region the branches of the parapodia proper have 

 become stouter and more elevated, the postsetal process being relatively smaller 

 and more slender and cylindrical, cirriform, often appearing only as short, post- 

 setal points, and the setigerous process proper often pointed and nearly equally 

 elevated. 



In the anterior region the setae are of two types, both simple. There are 

 the long, conspicuously acuminate and slenderly tipped capillary setae having 

 the characteristic camerated, or grated, structure, with serrated margin. The 

 cameration is absent proximaUy and over the slender tips. This type is found 

 exclusively in the notopodium, and occurs as well in the neuropodium in a fascia 

 much larger than that of the notopodium. (Plate 65, fig. 5). Besides these 

 there are in the neuropodium arranged commonly in a bow on the ventral side 

 of the circumference of the fascia, a number (often eight or ten) of much stouter, 

 spine-Uke setae. The greater part of each of these is buried, the free portion 

 being much shorter than that of the capillary setae. The free part is weakly 

 sigmoid, presenting a longer proximal curve with convexity dorsad and a short 

 distal curve with convexity ventrad. It narrows distally, the distal end being 

 acute. Each shows a fine, medullary, longitudinal fibrillation and, along the 

 dorsal half only, a transverse ridging, or cameration. (Plate 65, fig. 4). The 

 acicula are stout and colorless. 



Branchiae begin on the sixth somite. They are situated on the dorsum, 

 each a little mesad of a corresponding notopodium. All are simple, and a single 

 pair is present on each branchiferous somite. They are all flattened in the 

 cephalocaudal direction, and narrow from the base to an acute tip. The first 



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