1911.] NATURAL SCIENCES OF PHILADELPHIA. 281 



Ceratophores of cephalic tentacles, either not annulated or obscurely 

 3- or 4-annulate. Anterior paired tentacle reaches IV or V, posterior 

 paired XIII to XVII on different specimens, and median tentacle 

 usually to XX. Somite II is much enlarged, being fully double the 

 length of the peristomium, and its very large stout parapodia bear 

 three or four stout spines which reach quite to the anterior level of the 

 prostomium. Neurocirri of the first parapodium lie close to the sides 

 of the mouth; they diminish in size after the third foot (IV) and become 

 obsolete after VII. On different specimens the gills begin on from 

 XXVI to XXX and at their maximum development reach about three- 

 fourths of the width of the dorsum. They continue to the twelfth 

 segment preceding the pygidium, becoming rapidly reduced in size 

 toward the caudal end. Pygidium ending in a furrowed circumanal 

 ring directed dorsad and bearing a pair of subanal cirri arising in 

 contact, fiagelliform, very slender and as long as the last eleven seg- 

 ments or twice diameter of body. 



The distinctive features of the subspecies are found mainly in the 

 large posterior crochets and the jaws. The former (PI. XVIII, fig. 97) 

 have the terminal teeth continued nearly in the direction of the 

 shaft and not placed at a considerable angle with it as in most forms. 

 Pectinate setae have the plates bent into two-thirds of a circle with 

 very numerous denticulations. A young specimen (about 2 mm. in 

 diameter) still retains on the large spines of anterior parapodia traces 

 of terminal teeth and guards (fig. 96). 



The maxillae are long, with numerous teeth: II left side outer plate 

 18 teeth, inner plate 15 teeth, right side 17 teeth; III, left 9 teeth, 

 right 10 teeth; IV rudimentary with one tooth on each side. Mandi- 

 bles have the two sides entirely distinct. 



The anterior end of the body and the head are minutely speckled 

 with pigment. 



A typical example of the more than thirty tubes in the collection is 

 198 mm. long, 4.5 mm. in diameter at the small and 6 mm. at the large 

 end. Others vary from 72 mm. long and 3 mm. in diameter to 236 

 mm. long and 7 mm. in diameter, the great majority being about 

 200 mm. long. They are gently curved and tapered and toward the 

 larger end elliptical, not circular, in section, the diameter in the plane 

 of curvature being slightly less, indicating a dorso-ventral depression. 

 The tubes have a quill-like texture, but are harder and more rigid than 

 any quill of similar size and can be cut with a knife only with difficulty. 

 The maximum thickness of more than + mm. is at the middle, where the 

 number of layers is greatest and diminishes most toward the large end 

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