SALPIDJE. 



257 



SALPA MAXIMA (magnified) . 



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 dissimilar, but are either the parents or the progeny, as the case may be, 

 of the aggregated forms; and that chained Salpce do not produce chained Salpce, but solitary 

 tialpce, which in turn do not pro- 

 duce solitary but chained Salpce, 

 " so that a Salp mother is not like 

 its daughter or its mother, but 

 resembles its sister, its grand- 

 daughter, and its grandmother." 

 (Chamisso.) 



In the genus Salpa* the 

 animal is sub-cylindrical, being 

 truncated in front by the mouth- 

 opening, and pointed behind ; the 

 excurrent or anal orifice is placed 



beneath the pointed termination ; the body-covering is thin and transparent ; the muscular mantle is 

 incomplete, forming transverse or oblique bands ; the mantle cavity is lined with a series of sinuses, 

 or folds ; the gill is rudimentary, forming an oblique band across the interior ; the visceral cavity is 

 behind. The young are produced by gemmation in chains, consisting of individuals unlike the parent, 

 and becoming oviparous, the alternate generations only being alike. 



"The individual Salpians are from half an inch to ten inches in length ; the chains vary from a few 

 inches to many feet, but are often broken up, indeed the adults appear to be always separate. They 

 swim with either end foremost, although the pointed end would seem the normal one, as the motion 

 is produced by the forcible expulsion of water from the mantle. Each orifice is furnished with a 

 valve, and there is no division between the atrium and respiratory cavity except the rudimentary 

 gills, or ' hypopharyngeal band.' The Salpa-chains also swim with a regular serpentine movement. 



" The solitary Salpse always contain a chain of embiyos winding spirally round the visceral 

 nucleus. The aggregate Salpse produce a single ovum at a time, which is attached by a pedicle to 

 the posterior part of the respiratory cavity." (Huxley.) 



Genus Doliolum.^ The body is transparent, cask-shaped, open at the ends, and from two to 

 ten lines in length; the oral extremity is rather prominent, with twelve denticulations; the posterior 

 end is fringed. (Huxley.) There are two species known. They are found near Amboyna, Vanicoro, 

 and New Zealand. 



In Appendicularia\ the body is ovoid, one-sixth to one-quarter of an inch long, with a 

 long curved lanceolate tail, or swimming organ ; the smaller end is perforated, leading into a 

 cavity lined by a system of folds; the pharynx, which is ciliated, serves in lieu of a gill; the gullet is 

 short, curved ; the stomach is wide. (Huxley.) 



These minute creatures appear to be the lowest forms of the Tunicata, typifying, in their adult 

 stage, the larval state of the higher Ascidians. 



" When cruising," says Prof. Edward Forbes, "off the north coast of Scotland, in 1845, with 

 Mr. Robert McAndrew, our attention was attracted by the appearance of cloudy patches of red 

 colouring matter in the water, and on procuring a sample, and submitting it to microscopic ex- 

 amination, it was found to consist entirely of the curious and anomalous creatures known as 

 Appendicularice." Dr. S. P. Woodward writes : " Many small Appendicularice were taken in the 

 towing net (May, 1857) in the Channel, between Portland Bay and Ushant." 



Greek, salpc, a sea-fish. 



t Latin, diminutive of dolium, a large jar. 



t Lat., Appendicula, a small appendage. 



HENRY WOODWARD. 



223 



