TUNICATA 



669 



1. BOTRYLLTJS Gaertner. Colony thin and crust-like and embedded 

 in a common gelatinous tunic, the individuals being in circular, stellate, 

 or elliptical groups, in each of which they are arranged radially around 

 a common cloacal opening; incurrent opening widely separated from 

 the cloacal and near the periphery of the group; oral tentacles not 

 branched and few in number: about 24 species; principally in North 

 Atlantic and Mediterranean, in shallow water. 



B. schlosseri (Pallas) (B. gouldi Verrill) (Fig. 1,013). Colonies 

 massed thickly together on seaweed, stones, etc., forming gelatinous, 

 black or purplish incrustations sometimes 10 cm. or more in diameter, a 

 colony being made up of many groups, each group consisting of from 

 5 to 10 individuals and 3 to 6 mm. in diameter: Long Island Sound and 

 northwards; very common; Europe. 



Fig. 1,013 Botryllus schlosseri. A, a colony on a seaweed containing 7 groups 

 of individuals (Gould) ; B, diagram of a single group of individuals; C, diagram of 

 two individuals of a group with the common cloacal opening, the right-hand individual 

 in sagittal section (Delage and H6rouard). Explanations as in Fig. 998. 



2. BOTRYLLOIDES Milne-Edwards. Colony thin and crust-like, the 

 individual animals lying perpendicular to the surface and usually not 

 arranged in definite groups; the individuals lie along cloacal canals 

 which meet and open to the outside through a common cloacal pore: 

 over 2 dozen species. 



B. nigrum Herdman. Colony up to 7 cm. in diameter, very variable 

 in color, usually purplish or blackish; individuals about 1.5 mm. long: 

 Bermuda; in shallow water; common on stones and seaweed. 



FAMILY 2. DISTOMIDAE. 



Colony thick, sometimes stalked, usually embedded in a common 

 tunic; individuals consisting of thorax and abdomen, the viscera being 

 beneath the branchial sac, which is without internal longitudinal bars 

 or folds; openings each with 6 lobes: 10 genera, with about 80 species. 



DISTOMA Gaertner. Colony thick and fleshy, with the individuals 

 often in groups; intestine very long; branchial sac short: about 20 

 species. 



D. clarum Van Name. Colony jelly-like, transparent, 12 mm. in 

 width and half as thick ; individuals lying at all angles to surface, white 



