330 PROCEEDINGS OF THE ACADEMY OF [April, 



mentless have the anterior ones thus marked. Rarely this assumes 

 the character of a distinct ocellus as in Lepidasthenia gigas (Johnson). 



The tuberculatum of the elytra also varies, the larger smooth 

 papilhe, which are scattered among the numerous small corneous 

 prickle-, being elevated and conical or low and rounded, sometimes con- 

 fined to the first pair of elytra, sometime- present on all or nearly all. 

 Marginal cilia may be confined to the anterior elytra of commensal 

 specimens lint are longer and present on all elytra of free-living indi- 

 viduals, which also possess a tuft of five or six long ones just behind 

 the middle of the anterior border. The end of the notocirri may be 

 abruptly contracted as in Johnson's figure, or taper gently into the 

 terminal filament and this condition occurs independently of commensal 

 or free existence. Notopodial setal tufts are usually longer than 

 indicated in Johnson's figure and some of the dorsalmosl neuropodial 

 seta- bear an obscure accessory tooth or spur, and on commensal 

 individuals the dorsalmost pair of neuropodials may be much enlarged. 



Free-living examples of this species have much the general aspect 

 of Lepidonotus sublevis Verrill and L. clava (.Montagu), but of course 

 are readily separated by having eighteen instead of twelve pail's of 

 elytra and by other generic characters. Their neuropodial seta? 

 differ from those of commensals in being more slender and less strongly 

 hooked at the end and in having fewer (about 7) pectinated frills. 

 Besides being larger the elytra are also tougher and more horny and 

 the marginal cilia are longer. The distribution of the examples in 

 this collection suggests that other conditions than commensalism 

 may be effective in differentiating the two forms. 



The proboscis appears to differ in no way in the two phases, in 

 examples of both of which it is protruded. On a specimen 15 mm. 

 long it has a length of 2.6 mm. and a terminal width of 1.6 mm.; 

 one 40 mm. long has these measurements 5.5 and 3.2 mm. respectively, 

 the base being terete, the distal end depressed, with apertural papilke 

 f. Jaws massive and deep brown, the fangs very stout, compressed, 

 the ventral biting to the right; cutting plates well developed. 



Ehlers, 2 taking a comprehensive view of this and related nominal 

 species, unites, under the prior name of //. patagonica Kinberg, 

 H. brcrisetosa Kinberg, Polynoe chilensis Quatrefages, Lepidonotus 

 insignis Baird, Lepidonotus grubei Baird and, with some doubt, 

 Halosjjchw. parva Kinberg. His conclusion is partly based upon the 



'-' Festsch. Feier d. 150-jahr. Bestehens d. Konigl. Gesell. d. Wissensch. . z. 

 Go/lingcn, 1901, pp. 4.5-47. 



