78 THE ANNELIDA POLYCHAETA. 



as usual. The tip in those of the anterior somites is as long as the serrate portion 

 below it; it is but slightly curved, being convex on the abdental side and nearly 

 straight on the dentiferous, on which side is present a characteristic obtuse 

 angle a short distance below the apex, from which a slender tooth normally 

 projects distad; this tooth is easily lost; this subapical tooth was not found in 

 setae of posterior segments. The teeth of the most distal row are long, stout, 

 and acute; this row is followed by five to nine small series of teeth which dimin- 

 ish in size proximad. (Plate 5, fig. 2, 3). 



Locality. — Galapagos Archipelago: Chatham Island. 8 January, 1905. 

 One specimen taken on the shore. 



A well-marked species easily distinguished by its general form and the 

 size, structure, and relations of the elytra as well as by the structure, propor- 

 tions, and coloration of the prostomium and its tentacles and palps, and the 

 structure of the setae. It approaches L. versicolor Ehlers of the Chilean Coast 

 but differs conspicuously in its much stouter and differently formed palps, the 

 proportions of the other anterior appendages, form of head, structure of the 

 elytral tubercles, the larger smooth tip of the neuropodial setae and in other 

 details. 



Aphroditidae. 



In this family the body is proportionately broad and short, having an 

 oblong or subelliptic outline; depressed, with dorsum arched and venter flat. 



Prostomium distinct. Eyes usually two pairs, either sessile or pedunculate. 

 A single median tentacle with beneath it a distinct facial tubercle. Lateral 

 tentacles none, or rarely present (in Triceratia only). A pair of large palpi. 



Peristomium bearing two pairs of long tentacular cirri and mostly setigerous. 



Parapodia biramous, some bearing dorsal cirri and others elytra in their 

 place. The elytra occur on somites II, IV, and V, and on most of the succeeding 

 somites in alternating groups of twos or in the posterior region in part in groups 

 of threes; usually imbricated. 



Setae all simple, strongly developed. The dorsal setae long, consisting of 

 stout spines and finer capillary forms, directed typically upwards and backwards 

 over the elytra and dorsum. Capillary setae often iridescent, with hair usually 

 more or less felted over the dorsum and covering the elytra. 



Pygidium bearing two anal cirri similar to the ordinary notocirri. 



The proboscis bears no jaws, or these but rudimentary, ordinarily repre- 

 sented merely by thickened muscular prominences. 



