ANATOMY AND PHYSIOLOGY OF SALPA AM) PYROSOMA 5/ 



The " ciliated fossa " is compressed lateral!}-, and placed upon the 

 upper surface of a protuberance, formed by the ventral wall of the 

 respiratory cavity in the middle line. On each side a flattened 

 ciliated band (fig. lo x) runs up on the respiratory wall in front 

 of the anterior edge of the branchiae, and meets above with its fellow 

 of the opposite side. 



The " languets " are altogether eight in number. They extend in a 

 longitudinal series between the ciliated fossa and the mouth. The}- 

 are all slightly excavated and ciliated anteriorly. 



53. Immediately beneath the ciliated fossa, and in the midst of the 

 ventral sinus, lies the ganglion. This is about yio^^h of an inch long, 

 somewhat egg-shaped, with its large end forwards. Its posterior 

 extremity is in contact with a mass of deep red otolithes, fig. 10 d. 



A small nerve runs from the ganglion to the lateral ciliated band. 

 Five or six branches are distributed to the anterior aperture, and two 

 principal branches run backwards to the posterior aperture, giving off 

 branches to the mouth in their course. 



54. The Pyrosomata are hermaphrodite. 



The testis (/) is the so-called " hepatic organ " of Lesueur, Savigny 

 and Peron. It consists of ten, twelve, or more caeca, connected by 

 their posterior extremities, and here joining a central duct, which 

 opens by a papilla at the upper and posterior part of the respiratory 

 cavity. The spermatic sacs lie loosely in a dilatation of the vascular 

 sinus, and are bathed freely by the blood. 



Each sac is delicate and thin-walled, about 5^th of an inch in 

 diameter, and very variable in length. In adult specimens the distal 

 or anterior end of each sac is filled with a pale cellular mass. To- 

 wards the attached end this becomes darker and more distinctly 

 granulous, and the filiform bodies of masses of spermatozoa are 

 plainly perceived. 



The spermatozoa have narrow elongated heads and very long 

 delicate tails. 



55. There cannot be said to be any ovary properly so called. But 

 to the left, and rather in front of the testis (fig. 5), there could always 

 be found more or less decided traces of one or more ova. 



Commonly there was a single ovum (figs. 4-6), measuring about 

 Y-^o-th of an inch in diameter, with a clear germinal vesicle -g-^xr^h 

 of an inch in diameter, and a vesicular thick-walled germinal spot 

 r^V^th of an inch in diameter. 



The ovum is inclosed in a strong transparent sac, continuous with 

 a pedicle or gubernaculum (fig. 6 q), which runs to the upper and 

 posterior part of the inner tunic on the left side, and there terminates 



