MANUAL OF CONCHOLOGY. 



Class SCAPHOPODA. 



Cirrhobranchiata Blainville, Man. de Malacol. et Conchyl., p. 

 495 (1825-1832). 



Lateribranchiata CLARK, Ann. Mag. N. H. (2) vii, pp. 471, 476 

 (1851). 



"Solenoconches" Lacaze-Duthiers; Solenoconehce and Solenoconchia 

 of various authors. 



Prosopocephala BRONN, Klassen u. Ordnungen des Thier-Reichs, 

 Malacozoa, p. 523 (1862). 



Scaphopoda BRONN, t. c., p. 524 (1862). 



Bilaterally symmetrical mollusks with the shell (and mantle) a 

 long, more or less curved and tapering or fusiform tube, open at 

 both ends, the concave side dorsal ; anterior orifice larger, con- 

 tracted by a muscular thickening of the mantle, and giving egress 

 to the cylindrical head and the long, pointed foot, which is capable 

 of being enlarged and variously modified in shape distally ; the 

 smaller (posterior) orifice of mantle and shell giving exit to the 

 refuse of digestion, respiration and the genital products. Head 

 with terminal mouth surrounded by a rosette of lobes ; no eyes ; 

 otocysts present ; no tentacles, but a close cluster of thread-like, dis- 

 tally enlarged appendages known as captacula springs from the 

 base of the snout. Jaw and radula present ; liver two-lobed, sym- 

 metrical ; gut strongly convoluted, the anus opening rather far for- 

 ward in the mantle cavity, kidney openings near it. Gonad simple, 

 opening through the right nephridium. No gills, respiration being 

 performed by the general integument. Heart rudimentary, with 

 only one chamber, auricles and reno-pericardial ducts wanting. 

 Nervous system with well-developed ganglia, the cerebral, pleural, 

 pedal, visceral and buccal ganglia symmetrical. 



Marine animals, living partially imbedded in sand or mud on the 

 sea bottom. 



The tubular shell, open at both ends, is characteristic of the 

 group, and occurs nowhere else in the mollusca. Growth takes 



(v) 



