SALPA. 607 



The Salpians occur under two distinct conditions, being 

 at one time solitary, and at another associated into circular 

 or lengthened groups. These Satya -chains vary in length 

 from a few inches to many feet, and swim through the water 

 with a regular serpentine movement, but when taken from 

 the water the individuals of the group are easily detached. 

 Chamisso discovered that the solitary Salpce do not belong 

 to species distinct from those united in chains, however dis- 

 similar, but are either the parents or the progeny, as the 

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

 Salpce- do not produce chained Saljtce but solitary Salpce, 

 which in their turn do not produce solitary but chained 

 Salpce, hence giving rise to the paradoxical statement made 

 in the general observations on the Tunicaries. 



Genus SALPA, Forskal. 



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 sinuses ; gill rudimentary, forming an 

 oblique band across the interior ; visceral nucleus posterior. 

 Sexes combined. Young produced by gemmation in 

 chains, consisting of individuals unlike the parent and 

 becoming oviparous, the alternate generations only being- 

 alike. 



Syn. Thalia, Brown. Dagysa, Banks and Soland. 

 Biphora, Brng. Tethis, Tiles i us. Pegea, Jasis, Sa- 

 vigny. 



Ex. S. runcinata, Chamisso, (solitary form,) pi. 136, 

 fig. 3. S. runcinata, (aggregate form,) fig. 6, a. 





