SALPA. 9 



of the laiiguct, where we find the ciliated fossa (c./.). The large 

 triangular area (Figs. 1 and 2) within wliich the languet is placed 

 extends from the anterior end of the gill, and the vibratile cord 

 (c. 6.) which defines this vibratile cavity, as the area is called, en- 

 circles completely the anterior extremity of the respiratory system, 

 and occupies about one quarter of the length of the body. At the 

 angle made by the vibratile band, forming the edge of this cavity, 

 where the cord takes a dorsal direction, is placed the nervous gan- 

 glion (n.g.^, immediately behind the base of the languet; the gan- 

 glion is quite prominent, and sends numerous branches to the w^alls 

 of the body. A large vesicle attached to the ganglion contains 

 three irregularly shaped calcareous bodies, with deep black pigment 

 spots on the exterior side, making the nucleus a most prominent 

 object at the bottom of the ciliated cavity. The endostyle (e.) oc- 

 cupies nearly two thirds of the length of the body. The heart (A.) 

 is very prominent ; it is placed slightly to one side of the median 

 line, above the nucleus. 



Surrounding the nucleus (w.) is found a chain of diminutive 

 SalpcB (fZi.), extending in a circle from the right side of the nu- 

 cleus on the upper side to the opposite side, then running under it 

 and coming out on the opposite side again, and stretching toward 

 the median line. The young SalpcB are all attached by the poste- 

 rior extremity, exactly as we find colonies of fixed Ascidians and 

 Bryozoans, to a tube (g-. ^.), which is a simple diverticulum of the 

 circulatory system, and freely communicating with the gemmiferous 

 tube, as it is called. The young Salpce are not uniformly developed 

 in proportion to their distance from the base of the tube. Sections 

 of the tube are equally advanced, and we find generally three such 

 portions unequally developed, as has been noticed by Sars, Krohn, 

 Huxley, and others. The base of the gemmiferous tube is simply 

 slightly corrugated, next comes a section in wdiich we find two rows 

 of slight elevations, and finally the most advanced part of the chain 

 where the rudimentary Salpm are more or less advanced, and re- 

 semble in every respect, long before it becomes detached, the chains 

 which are found floating aliout. These sections are thus liberated 

 in turn, new ones continually forming at the base of the gemmifer- 

 ous tubes during the budding season. The part of the chain which 

 is the most advanced occupies, however, so much of the tube, that 

 the other sections are scarcely noticed. These chains escape 

 through an opening formed at the proper time through the tunic, 

 near the nucleus, on the ventral side, which shows afterwards no 



