1887.] NATURAL SCIENCES OF PHILADELPHIA, 301 



ion, and the number constituting a transverse row in one of the 

 cushions has been given by Leuckart^ as from four to twelve ; but 

 I find a much wider variation than this in the same and in different 

 individuals (fig. 7.). The number of ciliated ribs or cushions 

 also varies greatly, running from one hundred to two hundred. At 

 the anterior end of the gill two of the upper series of cushions are 

 continued out upon the wall of the branchial sac, and form the semi- 

 circular ciliated bands, which run obliquely around the anterior 

 extremity of the endostyle. 



The Endostyle of Salpa runcinata-fiisiformis (fig. 8) differs 

 considerably from that which has been so thoroughly described by 

 Fol'^ in various Tunicates, among others Salpa maxima, S. bicaudata, 

 S. pinnata, S. democratica. Running along each side of the endo- 

 style on the floor of the branchial cavity are the two ciliated bor- 

 der bands described by Fol (fig. 8, ebb.). In some specimens but 

 one of these bands appears to be ciliated, causing a lack of symmetry 

 as was early pointed out by H. Miiller and recently by Seeliger. They 

 consist of twelve or more thick cylindrical cells, bearing numerous cilia. 

 These bands are separated from the endostyle proper, by a space of 

 the ordinary pavement epithelium of the branchial sac. The "in- 

 ner" (Fol) "upper" (Uljanin) glandular cushion is usually in section 

 made up of thirteen or fourteen large columnar glandular cells poor- 

 ly defined from one another (fig. 8, igc). Those lying deepest in 

 the groove are the longest and thickest, giving the cushion a wedge- 

 shape, the apex forming the upper edge of the endostyle. The cells 

 of this cushion have a granular contents and present in the lower 

 third large bladder-like nuclei with relatively large and striking 

 nucleoli ; the upper portion of each cell is coarsely granular, and it 

 is difficult to say where the cell ends and the secreted matter begins. 

 Usually the two cells lying at the lower end of the cushion show a 

 longitudinal striation composed of dark bacillus-like spots. Accord- 

 ing to Seeliger these cells contain the pigment particles, probably 

 the coarse granules of my preserved specimens, which gives to the 

 endostyle its blue color. There is no "middle intermediary band" 

 present in the endostyle of Salpa runcinata-fusifarmis, the "inner 

 glandular cushion" resting directly upon the "middle glandular 

 cushion" (^igc. and mgc. fig. 8.). This is also the case with the 



1 1. c. p. 36. 



2 Fo/. {Hermann) : Ueher die Schleimdruse oder den Endortyl der Tun- 

 icaten. Morphologiscbes Jahrbuch. Vol. 1. 1876. 



