108 
THE VOYAGE OF H.M.S. CHALLENGER. 
what is called the “ flamboyant ” style. Consequently, in the following catalogue I have 
primarily grouped the species in three artificial, or perhaps natural, divisions or sections, 
distinguished respectively by their general habit or mode of ramification, though it should 
be understood that no very definite or abrupt limitation between them can be laid down. 
§ a. reticulata. 
Species in which the branches are connected so as to form a reticulate rather than 
fenestrate growth. Ocecia, when conspicuous, entire in front. 
(1) Retepora apiculata, n. sp. (PI. XXV. fig. 6). 
Character . — Zoarium of considerable size, irregularly flexuose, much folded, ex- 
panding. Meshes extremely irregular in form and size, 
often traversed by barren trabeculae. Zooecia obscurely 
rhomboidal ; primary orifice orbicular, with a wide secondary 
notch in front. Peristome rising on one side into one or 
two broad pointed teeth. Anterior avicularia prominent, 
rostriform, with an erect, acute beak mandible narrow, 
lanceolate, acute, horizontal. Ooecia lofty, contracted and 
hollowed in front, interiorly with a vertical median keel, 
and a depression on each side ; anterior lip of the opening 
trifid. Dorsal surface coarsely granular, with a few irre- 
gularly dispersed depressed retentive avicularia, with a wide 
three-pointed mandible. 
Habitat . — Station 172, Nukalofa, Tongatabu, 18 fathoms, coral mud. 
(2) Retepora producta, n. sp. (PL XXV. fig. 7). 
Character . — Zoarium rising from a rather broad base ; expanding very irregularly in a 
hypbcrateriform fashion, and very flexuose. Meshes elongated, narrow, acute at both 
ends, and of very irregular size. No barren transverse trabeculae. 
Zooecia urceolate, quite indistinct, orifice of the central ones deeply 
immersed, orbicular. Peristome level with the surface and unarmed, 
a rounded papillary eminence, usually on one side of the front. In 
the lateral zooecia the peristome very much produced, subtubular, 
pectinate, each denticle supporting a delicate articulated spine. A 
very minute labial fissure, one angle of which frequently supports a 
minute avicularium, with a semi-circular mandible. Ooecia incon- 
spicuous. Anterior avicularia very rare, with a long slender pointed 
mandible and usually a trifid beak (fig. 7f). Dorsal surface ( c ) divided into irregular 
Fig. 17 . — Retepora producta. 
