1905.] NATURAL SCIENCES OF PHILADELPHIA. 527 



prostomiiim. The surface is covered with minute prickles. The 

 frontal caruncle is a compressed, vertical plate as long as the prosto- 

 mium and much deeper, with its upper border thickened and somewhat 

 lobulated and its ventral margin forming an angle from which an 

 unusually long finger-like process depends over the mouth . The mouth 

 has the usual characters and is bounded posteriorly by III. The dorsal 

 tentacular cirri are about ^ and the ventral about + the length of the 

 palpi. 



Elytra to the number of 15 pairs occin- on the usual somites. They 

 are all thin, delicate, smooth and membranous and, except for a slight 

 brown incrustation on the middle ones, quite colorless. Being of large 

 size they cover the back completely and overlap medially. In the 

 middle region they are nearly orbicular and slightly emarginate, but 

 scarcely auriculate as in some species The scar is anterior to the center 

 and reaches to the lateral emargination. Those of the first pair are 

 narrowly ovate, extending over and concealing the head. The next 

 have the part anterior to the pedicle larger than that posterior. To- 

 ward the posterior end they become narrower and relatively much 

 longer. 



There are 15 pairs of "branchiae" (fig. .31) also, supported on somites 

 VI, VIII, X, XII, XIV, XV, XVI, XVIII, XX, XXII, XXIV, XXVI, 

 XXVII, XXIX and XXX. They arise from the extreme postero- 

 lateral region of the dorsum of their somites and are rather larger and 

 more complex than in many species. The medial side is high and rises 

 vertically to an angle from which the organ slopes laterally to the level 

 of the back, bearing the often bifid or trifid pinnae on its free sloping 

 margin. The number of terminal branches varies from 4 on the last 

 and 6 on the first to about 12 on the larger branchiae of the middle 

 region. The elytra and gills were studied on the type specimen only. 



Parapodia are of the usual form. The ventral cirrus scarcely reaches 

 the base of the second row of neuropodial setse. After tapering for 

 most of its length the cirrus is provided with a subterminal enlargement 

 followed by a constriction and a terminal ball. Dorsal cirri spring 

 from a large ceratophore and the long slender style is shaped distally 

 like the ventral cirri. Like the ventral surface of the body the 'para- 

 podia are thickly studded with spherical papillae of various sizes, the 

 larger ones increasing in number laterally and a group of especially 

 large ones occurring on the base of the ventral cirri, while slightly 

 smaller ones are closely crowded about the bases of the setae. 



On cirriferous somites the notopodial setae are arranged as follows: 

 A dense tuft of not very long capillary bristles springs from the ventral 



