258 Papers from the Department of Marine Biology. 



FAMILY POLYNOID^. 

 Lepidonotus inquilinus n. sp. 



Length of type 14 mm.; greatest breadth at end of anterior third 4 mm.; 

 body tapering from here in both directions, but the head is broader than the 

 pygidium. 



The head (plate 1, fig. 4) is oval with the transverse diameter the longer, 

 with a narrow median posterior depression and a much wider anterior one, the 

 latter filled with the base of the median tentacle. Posterior eyes very small 

 and situated on the dorso-posterior surface, the anterior ones larger, on the 

 antero-ventral surface, and not visible from above. At the anterior margin 

 the head is continued into the bases of the lateral tentacles, with a constric- 

 tion at the base of the latter. Lateral tentacle not more than half as long as 

 head, lanceolate, with acute tip. The other tentacles and tentacular cirri 

 had been lost. Palps about 6 tunes the length of the head, perfectly smooth. 



The body has 39 somites and 15 pairs of elytra. In alcohol the color is a 

 yellowish brown with no trace of pigmentation except on the elytra. On each 

 elytron a dark-brown pigment patch extends from the attachment of the 

 elytrophore toward the median longitudinal line of the body. This is crossed 

 by a definite white line at the position of the inner margin of the elytrophore 

 and does not reach the edge of the elytron. (Plate 1, fig. 5.) 



First parapodium (plate 1, fig. 6) with prominent antero-dorsal lip on the 

 neuropodium, the notopodium slender and cirrus-like, with an acicula and a 

 bundle of delicate, curved, minutely denticulate setae. The ventral cirrus is 

 very slender, reaching nearly to the tip of the neuropodium. A parapodium 

 from the middle of the body (plate 1, fig. 7) has the neuropodia and notopodia 

 much as in the anterior one, but the antero-dorsal lobe of the notopodium is 

 more acutely conical in form. The dorsal cirrus has a stout basal joint, its 

 terminal joint slender and tapering, extending beyond the apex of the para- 

 podium. The ventral cirrus is situated on the neuropodium about one-third 

 of its length from the apex. Each lobe of the parapodium has an aciculum 

 and the arrangement of setae is much as in the earlier somite. 



In the middle parapodium are three kinds of setae : 



(1) Notopodial: these are all alike, each seta being very long and slender, 

 curving gently toward apex and with very delicate teeth along one edge; fine 

 lines across the seta possibly indicate minute plates of which the teeth are the 

 free ends (plate 1, fig. 8). 



(2) Dorsal neuropodial : with long slender shafts, but with the terminal third 

 of the seta elongated lanceolate in forai; minute transverse plates in this 

 terminal third protrude from the margin so as to give it a minutely toothed 

 appearance (plate 1, fig. 9). 



(3) Ventral neuropodial : those lying next to the dorsal ones are much like 

 them in length, but have heavier shafts and the terminal swelling is shorter, 

 so that the lanceolate end is less elongated; the more ventrally placed ones 

 are shorter, so that those on the very ventral side are not more than half as 

 long as the dorsal ones; each (plate 1, fig. 10) has 5 or more rows of finely 

 toothed plates beyond the base of the lanceolate portion, with very fine trans- 

 verse plates between the last of these and the apex of the seta. The apex in 

 both kinds of ventral setae is bifurcate. 



Collected July 6, 1915, on a Marphysa from Mangrove Key, in Key West 

 Harbor. 



Type in American Museum of Natural History. 



