:Fam. 40.] NATURAL HISTORY SOCIETY. 125 



* Animal with no true tentacles ; front angl'.^s of the head pointed somewhat 

 like tentacles 5. Alderin. 



* Animal apparently with only 2 tentacles ; small, under 10 long. (A.) 

 A. With not over 5 large and 7 alternating, small, club-shaped gills on 



each side 6. StiUger. 



A Head produced into a fiat lobe on each side ; gills in a single row of 

 tufts, of 2 or 6 each, on each side 5. EmUetonia. 



A. Tentacles folded lengthwise; gills apparently like crosses...?. Hermcea. 



* Animal with 4 tentacles, and, in many cases, the front angles of the foot 

 prolonged into tentacular lobes. (B.) 



B. Animal under 10 long ; front angles of the foot rounded ; dorsal ten- 

 tacles longer. (O.) 



C. Foot rudimentary, branchiae in a single row on each side, each with 

 a sucker-like extremity 9. Tergipes. 



C. Anterior angles of foot rounded ; branchia' in distant transverse 

 rows 10. Galvina. 



B. Over 10 long. (D.) 



D. Width of body ^-^he length ...J.Eolis. 



D Width of body l~\ the length. (E.) 



E. Tentacles about equal in length ; dorsal ones perfoliate 



S. Flahellina. 



E. Tentacles usually unequal ; dorsal ones simple! (F.) 



F. Front angles of the foot not much prolonged, sometimes 



rounded 2. AioMia . 



F. Front angles produced into long, tentacular lobes..4. Coi^yphella. 



1. ^]OLIS, Cuv. 



Animal ovate; dorsal tentacles smooth, oval, slender; gills 

 simple, cylindrical, numerous, depressed, and imbricated ; foot 

 narrow. 



1. AwUs papulosa, L. Body broad, depressed, truncate in front, 

 rapidly tapering behind ; dorsal tentacles dark, of the same 

 length as the gills ; oral tentacles longer, more slender, and 

 lighter in color; gills lanceolate, compressed, short-stalked, ar- 

 ranged in many (12-20) imbricated, oblique rows on each side 

 of the back, and with 10-12 in each row ; central portion of the 

 back nearly naked, variously mottled, and showing the large 

 sack containing the pulsating heart. L. 30-70; W. ^ length. — 

 New Eng. Under stones between tides. 



2. ^^olis salmonacea, Cout. Body oblong, broad; tail suddenly 

 tapering to an acute point ; tentacles large and blunt, the dorsal 

 ones minutely serrated at the sides; gills rather long, larger and 

 pointed, 100 or more on each side, arranged in crowded, regularly 

 spaced series, orange red in color; foot broad, the front angles 



