368 BULLETIN 100, UNITED STATES NATIONAL MUSEUM 



On the young branches the peristome is little salient; the frontal 

 has the form of a shield, flat and quite visible. The characteristic 

 of the adult branches is formed by the presence of two large peristomial 

 tubercles surmounted often with a large spine. 



The small oral avicularium is more or less visible according to its 

 inclination; it is triangular and pointed in every direction. On the 

 interior the aperture is semielliptical and transverse and the micro- 

 metric measurements are somewhat smaller. 



Affinities. — In the almost identical dorsal and in the general aspect, 

 this species much resembles Reteporella longicollis, new species, but 

 differs from it in its never complete and little salient peristome, in 

 the presence of two large peristomial tuberosities and of a small 

 oral avicularium and in the spiramen fissure placed on the dorsal 

 (and not on the peristomie). It differs from Retepora pseudqftnis in 

 the presence of two peristomial tuberosities in the zoarial margins 

 normally arranged and in the absence of large perforations on the 

 dorsal lozenge shaped areas.. 



We have found a variety of this species in the Miocene at Bairns- 

 dale, Australia. 



Biology. — Our specimens were dead; it is not certain that the four 

 fragments from Mount Dromedario lived at the depth from which 

 they were dredged. The larva affixes itself only on small fragments 

 of shells, bryozoa, and pebbles. Although the waters of the Sulu 

 Archipelago ought to be very calm, there results, however, for the 

 colonies, a great instability of equilibrium which must be remedied 

 by the ensemble of zoarial organs as well as the system of ramifica- 

 tion. The cells are very small and the zoarium very thick; their 

 power of calcification is then very large. In the mode of the fixation 

 of its larva this species subsists only on the sand and shaly bottoms. 

 Occurrence. — 



D. 5137. Jolo Light, Jolo; 6° 04' 25" N.; 120° 58' 30" E.; 20 



fathoms; S. Sh. (common). 

 D. 5141. Jolo Light, Jolo; 6° 09' N.J 120° 58' E.; 29 fathoms; 



co. S. 

 D. 5151. Sirun Island, Sulu Archipelago; 5° 24' 40" N.; 120° 



27' 15" E.; 24 fathoms; co. S., Sh. 

 D. 5577. Mount Dromedario, Tawi Tawi; 5° 20' 36" N.J 119° 

 58' 51" E.; 240 fathoms; crs. S. 

 Cotypes— Cat. Nos. 8152-8155, U.S.N.M. 



RETEPORA PSEUDOF1N1S, new species 



Plate 47, figs. 12-14 



Description. — The zoarium is large, flabelliform, developed on the 

 same plane, width at least 4 cm. ; the fenestrules are quite large and 

 long (3 to 4 by 1 mm.); the dorsal is convex and ornamented with 



