38 U.S. NATIONAL MUSEUM BULLETIN 227 



May; induced to shed eggs in the Laboratory (Mead, 1897, 1898; 

 Bumpus, 1898a-c) ; none observed with eggs under the scales. Ras- 

 mussen (1956) found larvae in plankton in Denmark waters from 

 November to April, with a maximum in January and February; he 

 gives a detailed account of early stages. 



Harmothoe imbricata seems to have great powers of dispersal and 

 adaptation. Among the contributing factors, the following may be 

 mentioned: The habit of the female protecting the eggs by carrying 

 them under the elytra, the relatively long planktotrophic larval life 

 (Thorson, 1946; Rasmussen, 1956), and the adaptability to living 

 both free-living and commensally. According to Rasmussen, young 

 bottom stages of 9 or more setigers and 4 pairs of elytra may be 

 found in the plankton also. Larger individuals (up to 7-9 mm. in 

 length) may live as true bottom animals and for a time — before 

 fully grown — semipelagically, swimming brisldy in the water at some 

 distance from the bottom. An active swunmer, swimming by mak- 

 ing undulatory movements of the body. Very euryhalme, withstand- 

 ing rather fresh water (enters the Baltic and reaches into the interior 

 of the Gulf of Finland (Ditlevsen, 1937). Found in salt ponds of 

 low salinity in Rhode Island (Charlestown Pond, November 12, 

 1954, H. P. Jeffries). Withstands great range in temperature. 

 Great powers of accomodation bathometricaUy —while most common 

 in coastal areas, taken also from great depths (up to 2,030 fathoms 

 in southwestern Greenland). Great adaptability in habitat, living on 

 a great variety of bottoms. 



Material examined. — Numerous specimens from Labrador, Gulf 

 of St. Lawrence to Long Island Sound, intertidal to 150 fathoms. 



Distribution. — Widely distributed in the Arctic. Also Iceland 

 and Norway to Mediterranean and Adriatic, Labrador to New Jer- 

 sey, Bering Sea to southern Cahfornia, Japan, Yellow Sea, Indian 

 Ocean. In low water to 2,030 fathoms. 



Harmothoe dearborni Pettibone, 1955 



Figure 8g 



Harmothoe dearborni Pettibone, 1955, p. 121, fig. 3,a~i. 



Description. — Length up to 13 mm., width including setae up 

 to 4 mm., segments 35. Dorsally body rusty red with 2 narrow 

 white bands per segment. Elytra thin, transparent, rusty red with 

 white flecks, without fringe of papillae; elytral surface smooth except 

 for delicate scattered short papillae and scattered low microtubercles 

 which are mostly confined to the anterior half. Prostomium with dis- 

 tinct cephalic peaks, anterior third of prostomium dark brown. 

 Dorsal cirri pigmented on basal third and with a darker subterminal 

 ring. 



