118 CLASS IIT. 
capable, to a certain degree, of independent existence, and when 
fully developed, separates itself from the stem of the colony (Aby/a). 
In the Prayide, the covers are bounded by round surfaces above, 
and have a cavity below, like a helmet, to receive the other members 
of the group: in Diphyes they surround the stem like a rolled leaf, 
(differing, however, in form in the different species) and adhere to 
it by the narrow part. In Abyla they cover the members of the 
group imperfectly, are almost solid, yet with a cavity in the interior 
which is in connexion with that of the stem, and which is lined by 
large cells. In all these groups the sexual buds are more or less 
medusiform, and may be developed into a swimming bell. They 
sprout from the base of the Polyp.| 
Comp. on this family, besides the above work of Quoy and GAIMARD, 
especially Escuscuoitz, Syst. der Akalephen, s. 122, 123, LeUcKART Zoolo- 
gische Untersuchungen, 1. 8. 41—49, KoELLIKER Die Schwimmpolyp. s. 36— 
46: also Witt, Hore Tergestine, s. 76—83, GEGENBAUER in Zeitschr. f. 
wiss. zool. V. 8. 297—300. 
[Diphyes Cuv. The posterior swimming piece received into a 
-cavity of the anterior: the groups on the common stem protected by 
a bract or cover in form of a rolled leaf. 
Sp. Diphycs angustata Esouscu. Tab. x1. fig. 6 (the species of Bory seems 
to belong here ;)—Diph. campanulifera Escuscu., Quoy and GAIMARD 
Ann. des Se. nat. X. 1827, Pl. 1.; Diph. gracilis GEGENBAUER Zeitschr. fiir 
wissensch. Zoologie, v. 8. 309—315. Taf. xvi. fig. 5—7.—Diph. Siebolder 
Korn. Die Siphon. v. Messina, s. 36—41. Taf. x1. fig. 1—8.—Diph. gra- 
cilis GEGENB. Zeitschr. f. w. Zool. V. 8. 313—315. Taf. xvi. fig. 5—7.— 
Diph. Kochii Wit Hor. Tergest. Tab. 11. f. 22—26; figured without the 
posterior portion which WiLL did not meet with in any one of the six speci- 
mens examined by him?. 
Abyla Escuscu. Quoy and GArmMARD (Calpe of the same). 
The two swimming bells of very different size, the anterior much 
the smaller. The bracts cover the members of the groups imper- 
fectly, are massive, and have a cavity communicating with the 
stem. 
Sp. Abyla pentagona Escuscu., KoELLikER Die Siph. v. Mess. s. 41—46, 
Tab. x.; here the single polyps have no covers: see a complete specimen 
described and figured in Leuckart Zool. Untersuch., t. s. 56—61, Taf. m1, 
fig. 1—10. The bracts, or covers, which are not visible on the polyps at 
1 Compare also on this genus Lesson Centurie Zoologique, 1830, p. 161—183, 
Pl. 55—57- 
