VAN NAME: SIMPLE ASCIDIANS. 467 
Stigmata for the most part curved, and exhibiting a spiral arrange- 
ment on the infundibula, if not also elsewhere. 
Dorsal lamina usually plain-edged; less frequently with teeth. 
Reproductive organs on both sides of the body. 
This is the principal genus of the family and the most numerously 
represented genus of ascidians in the region covered by the present 
paper. Twelve species from the New England and eastern Canadian 
waters and one from the deep-sea are described here. 
In only two of the New England species of this genus (C. papillosa 
and C. citrina) were tailed larvae found in the peribranchial cavity 
or elsewhere in the body in the individuals examined. In those 
species they were present in most of the specimens. 
Synopsis of the New England Species. 
Body with a pedicel; five branchial folds crystallina. 
Body without a pedicel; six or seven branchial folds 2. 
2. Tentacles all unbranched; folds rudimentary singularis. 
Tentacles branched; except the smallest ones 3. 
3. Male and female glands separated by other organs; seven branchial 
folds retortiformis . 
Male and female glands forming hermaphroditic gonads 4. 
4. Each gonad with a long narrow dorsally directed oviduct; seven 
branchial folds citrina. 
Gonads without any oviduct, or with only a short neck 5. 
5. Rarely more than three internal longitudinal vessels on any fold. 
papillosa. 
Four or more internal longitudinal vessels on a majority of the 
folds 6. 
6. Body generally unattached, the animal living buried in sand 
or mud. 
Body laterally compressed, sand-covered, apertures far 
apart, interstigmatic vessels very narrow^ stigmata long; 
six branchial folds, right gonad bent dowTi around anterior 
end of kidney arenata. 
Body not laterally compressed, covered with moss-like hairs 
to which sand and mud adhere; six branchial folds, 
stigmata in large spirals, gonads short and broad, (deep 
water ofT the coast only) lutulenta. 
Body attached .... 7. 
7. Body of rather irregular form, surface rough; stigmata 
very short; apertures near or rather near together; 
six branchial folds robusta. 
