82 THE VOYAGE OF H.M.S. CHALLENGER. 
very small, trabeculate. Endotheca low down in the cup, very abundant; dissepiments 
very thin. 
This species resembles Symphyllia agaricia in many of its characters, but differs 
considerably in the width and depth of the valleys and in the size and number of its 
septa. The characters of its septa will readily distinguish it from Symphyllia radians. 
A small broken specimen was collected. 
Locality.— Banda. 
Genus 10. Lsophyllia, Milne-Edwards and Haime. 
Isophyllia, Milne-Edwards and Haime, Cor., ii. p. 374. 
Some of the opinions which have been held as to the affinities of this genus by 
different authors have been noticed under Symphyllia. 
The genus is essentially separated from Symphyllia by the characters of its septa. 
In Symphyllia the septa are strictly of the type of Mussa, being very thin near the 
centre of the calicle and increasing in thickness outwards, till at the margin they are 
very thick; and correspondingly the teeth of the septa are very thick and long at the 
margin, becoming very thin and small or rudimentary within. In Isophyllia, on the 
other hand, the septa are subequal within and without, being never markedly and dis- 
tinetly thickened at the margin of the calicle, although very prominent; while corres- 
pondingly the teeth are subequal throughout, and do not take on the JZussa type. 
Hight species of the genus were collected. 
1. Isophyllia strigosa (Duchassaing and Michelotti). 
Symphyllia strigosa, Duchassaing and Michelotti, Mém. Cor. des Antilles, p. 70, pl. x. fig. 16. 
A large and fine series of specimens of this species was obtained. Many of the speci- 
mens are very small and show somewhat irregularly the six lobes into which the simple 
ealicle becomes at first divided, while others attain to a size of 12 cm. in diameter. 
They are nearly hemispherical, sometimes slightly concave at the base, with an epitheca 
unequally developed ; the walls are wholly fused and thin, sometimes marked with a very 
narrow furrow above; the costze on the outer wall are generally well developed, lamellar 
and spinulose; the calicles may be isolated or in series of from two to six centres, being from 
15 to 25 mm. wide, and from 10 to 16 mm. deep; the septa are very thin in the young 
specimen, becoming thicker and more exsert in older ones; they are perpendicular or 
nearly so, more or less truncate and wide above and bear throughout their whole length 
subequal, long, acute teeth, which give a bristling appearance to the corallum; the 
columella is well developed ; and the number of septa to the centimetre is very variable 
even in the same specimen, being from seven to thirteen according as the last cycle is 
developed or not. 
