Rev. T. Hincks on the Genus Retepora. 355. 
(if not all) which are recognizable. If so, the number of known 
forms is remarkably small compared with the probable extent 
of the genus. 
The Retepores have a wide distribution in space, ranging 
from the Arctic seas to New Zealand and Australia, where 
they are represented by many species, and occurring in the 
Indian seas (Straits of Malacca &c.), at the Canary Isles, 
off Cape Horn, and on the southern coasts of North America. 
They have also a wide bathymetrical range, and have been 
taken at great depths as well as in comparatively shallow 
water. 
The new species which I am about to describe are in part 
Australian ; one of them is common to our own shores and 
to the Mediterranean; and one or two besides are inhabi- 
tants of the latter or of the Red Sea. 
The most important specific characters in this group are 
the structure of the oral aperture, the shape and size of the 
fenestre, and the form and position of the avicularian appen- 
dages. Some of the species are distinguished by a slit or 
fissure in the lower margin of the mouth, terminating below 
in a loop-like foramen; in others thisis wanting. ‘The genus 
may be conveniently divided into two groups, characterized 
by the presence or absence of the oral fissure. 
Class POLYZOA, J. V. Thompson. 
Subclass HoLopraNcHIA, HE. Ray Lankester. 
Group a. Ecrorrocra, Nitsche. 
Order GYMNOLZEMATA, Allman. 
Suborder Cheilestomata, Busk. 
Genus Rerepora, Lamarck. 
a. With an oral fissure. 
1. Retepora Couchti, n. sp. (Pl. XVIII. figs. 1-6.) 
Retepora Beaniana, Wincks, Devon and Cornw. Cat., Ann. & Mag. Nat. 
Hist. ser. 3, ix. 306 (50, sep.). 
Retepora e:llulosa, var. Beaniana, Manzoni, Bryoz. Foss. Ital. quarta 
contrib. 19, pl. v. fig. 26 (Sitzungsb. d. k. Ak. d. Wiss. Bd. lxi, 1 Abth. 
Marz-Heft, 1870). 
Zoarium irregularly cup-shaped, undulated and contorted, 
with asinuated margin, hispid. Menestre small, oval; stem 
short. Zooecia subcylindrical, depressed, except at the upper 
extremity, surface smooth ; orifice semielliptical, the front — 
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