TETHYDX. BOTRYLLID. 241 
Genus 2. BoTRYLLUS. 
Botryllus, Gertner, Savigny, Cuvier, Lamarck. 
The body is generally sessile, forming a gelatinous or carti- 
laginous mass, composed of rounded or elliptical projecting 
annular systems, situated in a circular cavity, with a distinct 
circumscription. 
The animals are disposed in a simple or many concentric 
series. The circular branchial aperture has no rays. The 
intestinal canal is short and narrow, prolonged into an apex or 
entangled with the membranaceous extensible cavity of the 
systems. The thorax is oblong; the respiratory covering has 
no papille on its meshes. The abdomen is less than the 
thorax, is semilateral, and is entangled against the bottom of 
the cavity containing the branchie. The ovaries are two, and 
are placed under the sides of the branchial sac. 
I. Botrylli stellati. The Animals of this section are dis- 
posed in a single series or range, their bodies are cylindrical, 
their apertures close together; and the branch of the central 
cavity is very short. 
1. Botryuuvus LEACHII. 
The body gelatinous, hyaline, with many very serrated 
systems, with ten or thirty cylindrical animals, with a hori- 
zontal stomach. 
Botryllus Leachii, Savigny, Mém. sur les Anim. sans Vert. 
Resch. sur les Ascidies comp. et simp. Fas. t. 198. t. xx. 
hes 3 
Inhabits the British Sea. I found this new species between 
Dover and Sandgate in Kent. 
The body of this species is composed of a gelatinous mass, 
rather flat, hyaline, tinged with reddish violet, with an infinity 
of vascular tubes of a yellow colour; the systems are very nu- 
merous, very much serrated, composed of ten or twelve indi- 
viduals, and sometimes twenty-five or thirty; with their sum- 
mits claviform, variegated with fawn and white; the branchial 
M 
