Rev. T. Hincks on the Genus Retepora. 357 
bruad at the base, slender and somewhat curved above, 
directed downwards. Ooecia small, suberect, semielliptical, 
closely adnate to the cell above, somewhat flattened in front, 
produced below into a truncate process, which reaches down 
some way within the aperture; a short and narrow fissure in 
the front wall. Dorsal surface very slightly vibicate, with 
many scattered elongate avicularia. 
Height (of fine specimens) about ? inch. 
Locality. For my specimens of this very beautiful species 
Tam indebted to R. 8. Newall, Esq., F.R.S. It was included 
amongst a number of Polyzoa which were said to have been 
taken from a telegraph cable in the Red Sea. On examining 
the collection, however, I find it to contain so many Mediter- 
ranean forms that I suspect there has been some mistake about 
the locality. Probably both Mediterranean and Red-Sea forms 
may be mixed in it. Mr. Newall is unable to clear up the 
point ; and I can therefore only refer the present species doubt- 
fully to the Red Sea. 
A large proportion of the specimens in the collection afford 
unmistakable evidence as to their habitat, the base from which 
they rise having been moulded on the cable and forming a 
cast of it. 
fi. pretenuis is one of the most beautiful of its tribe. 
Whether it ever assumes the caliculate form I am unable to 
say; but all the specimens which have come into my hands 
(about a dozen in number) consist of a simple reticulated ex- 
pansion. The fenestre are usually much elongated, and the 
inosculating branches which compose the network remark- 
ably slender, giving an air of great lightness and delicacy to 
the whole structure, which is very slightly put together and 
extremely fragile. The oral fissure is very small, almost 
rudimentary, and is associated with a minute, rounded avicu- 
larium, rising from the lower margin beside it. The peristome 
is very slightly developed; and the structure of the oral aper- 
ture is essentially simple. ‘The elongate and pointed avicu- 
laria are not present on every cell; but on every specimen a 
considerable number may always be met with, and they form 
a good distinctive character. They are raised on a mound- 
like elevation ; and the slender acuminate mandible points, as 
a rule, straight downwards. ‘The ovicell presents some very 
marked peculiarities. It is small and decidedly suberect ; the 
front wall is flattened, and is prolonged below into a kind of 
lamina, subtruncate at its lower extremity, which extends 
some way into the aperture. The fissure is very short and 
narrow, and is not open below. 
