TUNICATA. 341 



Tribe 1, Botryllina — Botryllians. 

 BoTRYLLUs, Gaertner, 1774. 



Etym. Botrys, a cluster of grapes. 



Syn. ? Pyura, BL Polycyclus, Lam. 



Bx. B. violaceiis, PI. 24., fig. 8, two stars from a group. 



Test gelatinous or cartilaginous, iucrusting ; systems numerous, promi- 

 nent, round or star-shaped, with central cavities ; individuals 6 — 20 in each 

 system, lying horizontally, with the vent far from the simple branchial oritice. 



Bistr. 10 sp. U. States, Europe. Brit. 6 sp. On stones and sea-weed 

 near low-water mark. B. violaceus is greenish grey, with dark blue stars, 

 yellow in the centre round the common orifi^ce. B. 7-acemosus, N. Zealand. 



BOTRYLLOIUES, M. Edw., 1841. 



Ex. B. rotifera, PI. 24, fig 9, a zo'id detached, with a cluster of repro- 

 ductive germs. 



Animals nearly vertical, in star-like groups irregular and ramifying; 

 cloacae prolonged into the common mass, forming irregular channels, along 

 each side of which the individuals are placed in linear series ; orifices closely 

 approximate. 



Distr. Em-opean coasts, on roots of sea-weed and under sides of stones 

 between tide marks. Brit. 4 sp. 



Tribe 2, Didemnina. " Didemnians." 

 Division a, unistellate, (oral orifice rayed.) 



DiDEMNIUM, Sav. 



Etym. Di'demnium double-couch (or cavity). 



Ex. D. gelatinosum, PI. 24, fig. 10, zo'id detached. 



Test coriaceous, polymorphous, incrusting ; systems numerous, com- 

 pressed, without central cavities or distinct circumscription ; individuals 

 scattered ; abdomen pedunculate ; ovary by the intestinal loop, increasing 

 in length when the ova are fully developed. 



Bistr. Europe. 



EucGELiuM, Sav. 



Etym. Eu'koilios much excavated. 



Ex. E. hospitiolum, PI. 24, fig. 11. 



r^5^ gelatinous, incrusting ; systems numerous, without central cavities 

 or distinct circumscription : animals scattered or arranged quincuncially 

 branchial orifice circular ; anal minute ; abdominal viscera beside the thorax. 



Bistr, Europe. 



Leptoclinum, M. Edw. 

 Etym. Leptos thin, kline tunic. 



