SALPA. 9 



of the languet, wlicre we find the ciliated fossa (c./.). The large 

 triangular area (Figs. 1 and 2 ) within which 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 res])iratory 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 tlorsal direction, is placed the nervous gan- 

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

 glion is quite ])r()minent, and sends numerous branches to the walls 

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

 three irregularly shaped calcareous bodies, with deep l)lack pigment 

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

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

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

 is very prominent ; it is |)laced slightly to one side of the median 

 line, above the nucleus. 



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

 Salpcc Qch.^, extending in a circle from the right side of the nu- 

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

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

 the median line. The young Salpcs are all attached I\y 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 

 tulje, as it is called. The young Sa/p(s are not uniformly developed 

 in proportion to their distance from the base of the tul)e. 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 which we find two rows 

 of slight elevations, and finally the most advanced ])art of the chain 

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

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

 which are found floating about. These sections are thus liberated 

 in tm-n, now 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 ])roper time through the tunic, 

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



