114 THE VOYAGE OF H.M.S. CHALLENGER. 
inner margin of the septa. Synapticule distant, very unequally and irregularly 
developed, being generally rather thick, interseptal outgrowths of the upper part of 
the wall. Endotheca well developed, deep down, easily seen in a vertical section. A 
transverse section shows the calicles with distinct centres generally arranged in sinuous 
valleys, which are bounded by thick and solid walls. 
This genus is close to Pavonia, in some species of which an approach is made at the 
apical parts of the corallum to the arrangement of the calicles in isolated and sub- 
sinuous groups with elevated and solid walls. In Tichoseris, however, the walls are 
elevated at all parts of the corallum, the interseptal chambers are extremely deep, the 
dissepiments being inconspicuous from above, and the sinuous and meandrine arrange- 
ment of the calicles well marked. 
Tichoseris obtusata, Quelch (Pl. V. figs. 3-8c). 
Tichoseris obtusata, Quelch, Ann. and Mag. Nat. Hist., vol. xiii., 1884, p. 296. 
Corallum consisting of blunt, elongated or rounded, lobate masses, of very dense 
structure throughout. Calicles small; often separate, subcircular or elongated and poly- 
gonal, from about 3 to 5 mm. in diameter, deep, but often appearing almost filled up 
and shallow, owing to the closely packed septa; more generally from two to six or more 
ealicles are grouped together, with their walls incompletely developed, so that they give 
the appearance of many centres surrounded by one raised wall, which is of very regular 
shape and size, being long, sinuous, meeandrine, and narrow, or rounded and wide, often 
from 5 to 14 mm. in diameter. Wall very solid throughout, thin-edged above, but thick 
below. Septa not exsert, very numerous, in the separate calicles there are as many as 
five cycles, but the fifth is very incomplete; those of the first two cycles are subequal 
those of the fourth and fifth very small; but all are entire, very thin, extremely granu- 
lated or finely echinulated on their sides, with their inner edges nearly vertical. Colu- 
mella very rudimentary. Dissepiments very thin, and rather widely separated. 
Two small specimens of this species were obtained. 
Locality.—Reefs, Fiji. 
Genus 8. Pavonia, Lamarck. 
Pavona (pars), Lamarck, Syst. Anim. sans Vert., p. 382, 1801. 
Pavonia (pars), Lamarck, Hist. Anim. sans Vert., 11. p. 238, 1816. 
Lophoseris, Milne-Edwards and Haime, Cor., iii. p. 65. 
FA Duncan, Rev. Madrep., p. 157. 
As Verrill’ points out, Lamarck’s application of the name Pavonia claims priority 
over Hiibner’s use of the term for a genus of Lepidoptera, and it must therefore be 
retained. The dissepiments, which were not noticed by Milne-Edwards and Haime, 
have been described by Verrill, as already stated. 
Five species were obtained. 
1 Trans. Connect. Acad., vol. i. p. 543, 1868. 
