SALPIDA. 47 



Behind this is the peripharyngeal band (16), which is grooved 

 in the usual manner. 



The nervous system and the organs of sense, in correspondence 

 with the power of free locomotion, present a higher grade of 

 development than in the Ascidiacea. The ganglion (13) with its 

 numerous nerves lies dorsal to the anterior attachment of the 

 " gill " and is of considerable size. It has on its dorsal side a 

 horseshoe-shaped brownish-red pigment band, in which are con- 

 tained besides the pigment numerous rod-shaped structures, 

 the whole directly resting on and being part of the ganglion. 

 There can be but little doubt that this structure is an eye. 



The dorsal tubercle (ciliated pit) is a short diverticulum of the 

 pharynx in front of the peripharyngeal band ; it is without a 



Fia. 40. Salpa in longitudinal vertical section, seen from the left side, diagrammatic. 1 

 mouth ; 2 atrial aperture ; 3 anus ; 4 pharynx (branchial sac) ; 5 " gill " (dorsal lamina) ; 

 6 duct of subneural gland ; 7 endostyle ; 8 heart ; 9 oesophagus ; 11 languet ; 12 muscle- 

 bands ; 13 nerve ganglion ; 14 embryo in ovisac ; 15 atrial cavity ; 16 peripharyngeal 

 ring ; 17 stomach ; 18 testis ; 19 test ; 20 subneural gland ; 21 dorsal tubercle. 



glandular part and does not extend as far back as the ganglion 

 (21). On the ventral side of the ganglion there are two glands 

 (subneural glands) which open by separate orifices into the 

 pharynx (or atrial cavity ?) just in front of the peripharyngeal 

 band (6) and behind the representative of the dorsal tubercle. 

 There are no otocysts in salps. 



The pharynx is without any side walls or stigmata and freely 

 communicates with the atrial cavity on each side. The endo- 

 style (7) is present in the usual form, and the dorso-median wall 

 of the pharynx is represented by the so-called gill (5) which takes 

 an oblique course across the body from near the ganglion to the 

 opening of the oesophagus where it terminates. The oesophagus 

 (9) leads into a gut which possesses a stomach and pyloric gland. 



