24® Introduction to Animal Morphology. 



round opaque mass at one end of the body (nucleus) in 

 Salpa, but not in Salpella. Anchinia has no muscular bands 

 for locomotion. 3. Doliolidae — barrel-shaped, with equal, 

 regular, hoop-like, circular muscle-bands ; gill cavity flat. 

 4. Pyrosomatidas — stock a cylindrical tube open at one end, 

 made up of many individuals united ; each persona opens 

 outwards and inwards by its polar mouth and cloacal openings 

 respectively. The gill sac is like that of an Ascidian proper. 

 Each e.^^ develops four individuals, which rapidly multiply 

 by buds from the endostyle. 5. Kowalewskiidae — heart, en- 

 dostyle, and intestine absent ; pharynx ciliated with four rows 

 of teeth, otherwise as in Appendicularia. 



Order 2. Chthonascidise {Broivji) — fixed, rarely imbedded 

 in sand or mud ; mouth and cloacal opening at one end more 

 or less tubular, with the ganglion between them ; branchial 

 sac regular, with many rows of gill slits. 



I. Pelonaiadae — imbedded in mud; individuals united, 

 with no heart and symmetrical sex organs. 2. Ascidiadse — 

 fixed to stones, having a heart, undergoing metamorphosis in 

 development; sex organs unsymmetrical. Chelyosoma is 

 flat, and has the peculiar many-angled plates above described. 

 Rhodosoma has a two-winged cutis. Boltenia is long stalked, 

 with four rayed openings and compound tentacles. Cystingia 

 is similar, with an irregular anus. Dcndrodoa has a longitu- 

 dinally folded gill sac and a tentacle crown, and one (left) 

 ovary, while Cynthia has two and Pandocia has one ovary 

 (the right). Molgula has no longitudinal folds in the branchial 

 membrane, an eight-lobed mouth and a six-lobed cloacal 

 opening. Phallusia has a six-lobed mouth and a four-lobed 

 atrial outlet. 3. Clavellinidce — family stock branched, with 

 stalked personge, and often with common circulation. There 

 may be creeping stolons (Clavellina), or a single stolon with 

 a few individuals (Perophora), or in compound, greenish, 

 large masses (Syntethys). In Chondrostachys the individuals 

 are grape-like on an upright stem. 4. Botryllinidas — com- 

 pound, usually forming an expanded, mucous, or spongy, 

 often lobed mass, united by their common cutis, but without 

 common circulation. They are divided into three sub-fami- 

 lies : — (a). Botryllinse — having the personoe united around 



