VoL. 2] Ritter—The Pelagic Tunicata. 53 
PYROSOMIDAE. 
Pyrosoma giganteum, 
Of these, Cyclosalpa bakeri and the trophozooid of Doliolum 
tritonis have not hitherto been described. 
Class UROCHORDA Lankester (Tunicata, Lamarck). 
Order I.—THALIACEA Van der Hoven. 
Pelagic urochorda, with body of zooid more or less eylin- 
drical, the branchial and atrial orifices being situated at oppo- 
site ends, or nearly so, of the body. Mantel musculature limited 
almost entirely to encircling fibres, these being grouped into defi- 
nite bands. Propagation through an alternation of heteromor- 
phie oozooid and blastozooid generations. 
Fam. I.—SaAupipak, Forbes, 1853. 
Thaliacea in which the branchial stigmata are reduced to a 
single pair, each very large, between which, extending the entire 
length of the great pharyngeal cavity, is a prominent vascular 
band known as the gill. Muscle bands rarely extending around 
the body without interruption, the break usually being on the 
dorsal and ventral sides. Oozooids and blastozooids presenting 
each one form only. 
Genus 1.—Cyclosalpa, DeBlainville, 1827. 
Thalia, Browne, 1756. 
Salpa, Forskahl, Cuvier, Traustedt, and most writers. 
Cyclosalpa, Herdman, Lahille, Apstein. 
Salpidae in which the intestine never forms a compact spher- 
ical mass known as the ‘‘nucleus,’’ but is either extended along 
the dorsal side of the ‘‘gill’’ as a straight tube, or disposed in a 
large ring. Blastozooids set free from the proliferating stolon 
of the parent in circular groups, or whorls. 
Genus 2. Salpa, Forskahl, 1775. 
Holothuria, Linn, 1758. 
Dagysa, Banks and Solander, 1773. 
Biphora, Bruguiére, 1789. 
Tethys, Tilesius, 1802. 
Pegea, Savigny, 1816. 
Jasis, Savigny, 1816. 
Pterolyra, Lesson, 1830. 
Dubrieullia, Lesson, 1830. 
