EYES AND NEURAL GLANDS IN CYCLOSALPA. 2O3 



laterally-directed rod-cells o{ Cyclosalpa dolichosonia-i>irgnla(com- 

 pare Fig. 8, //'), and these cells in the two species are probably 

 homologous, the rod-cells in Cyclosalpa dolichosoma-virgula hav- 

 ing developed from intermediate cells. A few intermediate cells lie 

 posterior to the dorsal pigment curtain (Fig. 12, q'}. The group 

 of spindle-shaped cells in the eye of Cyclosalpa dolichosoma-virgula 

 occupies a similar position (compare Fig. 5, q). 



The ectoderm (Fig. 12, <w), closely covers the entire eye and 

 dorsal surface of the ganglion, except at the postero-dorsal 

 angle of the ganglion. A membrane (Fig. 12, z), continuous 

 with the ganglionic membrane, meets the ectoderm posterior to 

 the ganglion, shutting off a small chamber (Fig. 12, oc], which 

 is homologous with the posterior portion of the optic chamber 

 of other species, such as Cyclosalpa dolic/iosojna-i'irgula. The 

 limiting membrane of the optic chamber (Fig. 12, ^r), described 

 for Salpa pnnctata is not found in Cyclosalpa doliclwsoma-virgnla. 

 It is present in many other species, and its absence in Cyclosalpa 

 dolichosoina-i'irgnla is exceptional. 



The ectoderm, after covering the eye and ganglion, turns 

 abruptly dorsalward, so that the eye and ganglion lie just under 

 an ectodermal invagination. This invagination thus forms a 

 supra-neural ectodermal chamber which is filled by an unusually 

 dense portion of the tunic (Fig. 12, sc\ It has a somewhat 

 triangular dorsal opening to the exterior. The supra-neural 

 ectodermal chamber in Salpa pnnctata probably serves for the 

 eye and ganglion a similar protective purpose to that of the large 

 optic chamber of Cyclosalpa dolichosoma-mrgula. A similar 

 ectodermal invagination is found above the ganglion of the im- 

 mature Salpa rnncinata-fnsifonnis, chain form. 



The latero-ventral outgrowths from the ganglion to the neural 

 glands are similar in structure to those of Cyclosalpa dolichosoma- 

 virgula, but smaller. The wall and duct of each gland are 

 composed of a single layer of cells. That portion of the wall 

 next to the ganglion is thickened by the elongation of the cells 

 but these cells even here form a single layer. This is unlike 

 the condition found in Cyclosalpa dolicliosoma-virgnla, in which 

 the thickening of the gland wall next to the ganglion is caused 

 by the presence of several layers of cells. The gland ducts of 



