. 87 



area well defined, Hat ; foramen large, incomplete ; deltidia small ; 

 dorsal valve with a central longitudinal groove ; apophysis central, 

 bifurcating ; margins of the valves thickened internally and spiuulosc. 

 Length, '25 ; breadth, "25 ; height, "12. 

 Australia. 



ORDER SCLEROBRACIIIA. 



The oral arms support a shelly band arising from the cardinal edge 

 of the ventral valve ; shell not perforate. 



FAMILY EIITNCHONELLID.I:. 



Oral arms elongate, fleshy, supported at the base by two short, 

 hard, diverging shelly lamina) arising from the hinge margin of the 

 ventral valve ; unpimctate. 



RHYNCHGNELLA. 



Trigonal, acutely beaked, usually plaited ; dorsal valve elevated in 

 front, depressed at the sides ; ventral valve flattened, or hollowed along 

 the centre, hinge plates supporting two slender curved lamella? ; dental 

 plates diverging. 



Hudson's Bay. Japan. 



8. R. iligricans, Sowcrly, T/ics. ConcJi., \.,p. 34-2. Thin, irregu- 

 lar, longitudinally ribbed ; margin crenulated. Brown or blackish. 

 Length, '7 ; breadth, '8 ; height, '4. 



Not uncommon in the South. Chatham Islands. 



ORDER SARCICOBRACHIA. 



Oral arms fleshy to the base, without any shelly support; the lower 

 valve without any processes on the hinge margin or disc, except some- 

 times a slight median longitudinal elevation. 



FAMILY CRANIADVE. 



Upper valve conic ; animal attached by the outer surface of the 

 ventral valve. 



CRANIA. 



Smooth or radiately striated ; umbo of dorsal valve sub-central ; 

 of ventral valve sub-central, marginal, or prominent and cap-like, with 

 an obscure triangular area traversed by a central line. 



Spitzbergen. Europe. India. Australia. 



9. C., sp. ind. Dorsal valve rugose, with a few radiating lines in 

 places ; ventral valve smooth. Light brown. Diameter about "5. 



Class Polyzoa. 



Alimentary canal suspended in a double walled sac, capable of being 

 partially protruded ; mouth surrounded by a circle of hollow ciliated 

 tentacles ; animals always composite. 



