POLYCHyETA OF THE FAMILIES SERPUL1D.-E AND SABELLID^E. 95 



very small crowded segments anteriorly, in which no tori could be distinguished. Tin; 

 branchial crown was represented by two small buds with four finger-like projections. 



No tube was present, but to one specimen was adhering a minute portion of a 

 rather thin membrane, to which very small sand-grains were fixed, and this may have 

 been a portion of a tube. 



With these also was a larger specimen (8 mm. total length), in which no pigment 

 spots were present, but which otherwise seemed identical with this species. 



The pigment spots in Eurato (Xl><ll) mn'icata (9, p. 255) are differently 

 arranged. 



This is apparently the first time that this species has been recorded since SCHMARDA 

 described it from Jamaica in 18(51. 



Genus Potamilla Malmgren, 1865 (13, pp. 401 and 402). 



Generic characteristics : 



1. Thoracic tori, double rows, consisting of avicular crotchets and pennoued 



setse respectively. 



2. Abdominal tori, single rows of avicular crotchets. 



3. Collar present. 



4. Thoracic setse of two forms dorsally a few with simple blades, ventrally 



spathulo-mucronate. 



5. Abdominal setse simple blades. 



tj. Branchial crown not markedly spiral, and without sub-terminal eyes on 

 rachises. 



Potamilla unturctica Gravier, 190(5 (7, p. 59). 



1. Branchire seventeen pairs, with no trace of eyes, about one-fifth the length 



of the body. 



2. Avicular crotchets of thorax and abdomen of characteristic shape (see Gravier 



(8) and (7) for figures). 



Localities. One specimen from shore pool at Station 349, Tussock Island, Falkland 

 Islands ; seven incomplete specimens, all of which had lost their branchial crowns, from 

 the shore at Station 118, Cape Pembroke, Falkland Islands. 



The tubes of the latter specimens are much overgrown by a colonial tunicate. 



The anterior part of the tube of the Tussock Island specimen contained numerous 

 larvte, 5 mm. long, and having five or six segments. The specimen in the tube was 

 well preserved, and was 31 mm. in length, of which the branchiae made up (5 mm. 



The other specimens are, without their branchial crowns, 27 mm. long and 3 mm. 

 wide, and have nearly parallel sides only a few of the terminal segments being 

 narrower. The thorax consists of eight setigerous segments, and the abdomen of 

 about fifty. The setse were in nearly every segment broken off below the blade, and 



(ROY. soc. EUIX. TRANS., VOL. XLIX., :',.~>.~j.) 



