212 ALLAN HANCOCK PACIFIC EXPEDITIONS VOL. 15 



have well developed parapodia and the prostomium is fully uncovered. 

 These features ally them to the suborder Errantia. The body is divisible 

 into an anterior thorax and a posterior abdomen and the eversible 

 pharynx is unarmed ; these characters are those of the Sedentaria. Orbi- 

 niids inhabit mainly the intertidal or littoral zones but a few species are 

 described from greater depths. They are most abundant in shallow 

 marine seas where they are associated with sandy or muddy bottoms or 

 algal holdfasts. They sometimes occur in massed numbers so as to form 

 beds. One species is known from a brackish lake in India and none from 

 freshwater. 



Most species are recorded from temperate or warm seas but large 

 numbers of individuals of a few species occur in polar seas. Geographic 

 distribution is so checkered that some large continental areas have up to 

 20 species and others have few or none (see charts of distribution 

 below). 



Orbiniids attain dimensions of considerable size with a length of 

 400 mm not unusual; most are moderately large and measure 35 to 100 

 mm long; and a few are minute, measuring only a few millimeters long. 



Historical 



The oldest generic name, Aricia Savigny, was erected for A. 

 sertulata Savigny, 1820, from La Rochelle, France. The same species 

 from this locality was later (1833) named Aricia cuvieri Audouin and 

 Milne Edwards. Savigny had attributed to the prostomium the presence 

 of four rudimentary antennae, for which he mistook the everted nuchal 

 organs. This interpretation led to a discussion by later authors on the 

 merits of one name against the other. Most are now agreed that the two 

 specific names refer to the same species but have preferred the use of the 

 younger name, A. cuvieri Audouin and Milne Edwards since it has 

 received the greatest usage and is best described (Fauvel, 1927a, p. 12) ; 

 I follow this usage for the specific name. 



The family name was more recently erected although its major 

 groupings were noted when Audouin and Milne Edwards (1833, pp. 

 388-399) used ARICIENS for Aricia Savigny with three species {A. 

 cuvieri, A. latreillii and A. sertulata) , together with some species in the 

 Spionidae, Opheliidae and Cirratulidae. 



Castelnau (1842, p. 20) in a brief and obscure reference erected a 

 name Venadis (not to be confused with Vanadis Claparede, a pelagic 

 Alciopidae) for Aricia cuvieri and A. latreillii. Venadis was proposed to 



