SALFA. b 



toiy cavity ; anal orifice terminating close al)Ove, and to the right 

 side of, the nioutli. Alternately solitary and aggregated. 



The Salpians occnr under two distinct conditions, being at one 

 time solitary, and at another associated into circular or lengthened 

 groups. These Salpa-vha'nm vary in length irom a few inches to 

 many feet, and swim through the water with a regular serpentine 

 movement, liut when taken from the water the individuals of the 

 group are easily detached. Chamisso discovered that the solitary 

 Salpcc do not belong to species distinct from those united in chains, 

 however dissimilar, but are cither the parents or the progeny, as 

 the case may be, of the aggregate forms ; and that chained Salpa 

 do not produce chained Salpcc, but solitary Salpa, which in their 

 turn do not produce solitary but chained Salpa, hence giving rise 

 to the paradoxical statement made in the general ol)servations on 

 the Tunicaries. 



Ocntis SALPA, Forskal. 1775. 



Animal oblong, sub-cylindrical, truncated in front by the oral 

 orifice, pointed posteriorly ; anal orifice sub-terminal ; test thin, 

 gelatinous, transparent ; muscular mantle in the form of transverse 

 or oblique bands ; mantle cavity lined by a system of vascular si- 

 nuses ; gill rudimentary, forming an ol)lique band across the inte- 

 rior ; visceral nucleus posterior. Sexes coml)ined. Young produced 

 by gemmation in chains, consisting of individuals unlike the parent 

 and becoming oviparous, the alternate generations only being alike. 



Krohn makes three types, to which all the variations of the asso- 

 ciated Salpcc are reducible. The first is characterized by the ver- 

 tical position of the animals forming the chain, the axes of their 

 l^odies crossing the axis of the chain at a right angle. In the sec- 

 ond the bodies of the individuals are more or less inclined to the 

 axis of the chain. The third group is distinguished by the hori- 

 zontal position of the component animals, the axes of their bodies 

 being more or less parallel to the axis of the chain. 



