BULLETIN 5!), UNITED STATES NATIONAL MUSEUM. 91 



COXCLUDINC RK.\L\RKS ON l'< jCILLoroRA CKSPITOSA. 



Following nil account of the \ariation, tliosp cliaractcr.s wiiich all of llic spci-inicns 

 havo ill coiiiinon should lie iiulicatcd. 



The tirst coiiiinon character is size. The colony always forms a small clmii|). 

 the laro;est individual of which is scarcely In cm. full. The verruc.e when present 

 are irreg-ular in development, having the appearance of hranclilets that failed to 

 develop, and there is abundant intergradation between vernicit and hraiichlets. The 

 crenenchymal surface is granulate, the coarseness of the granulation variable. The 

 calices vary in diameter from 0.4: to about 1 mm. The septa and columella vary from 

 ob.solescent to distinct. It will therefore be seen that the specitie characters consist 

 in the size of the coralliim and the character of the branchlets or verruca'. 



This species has been reported by Quelch" from Tahiti; by Orlmaiin'' from 

 Ceylon; and by Gardiner •" from Wakaja, Fiji Islands. References to these deter- 

 minations have been omitted from the synonymy given in this memoir. 



The A/fiofro.is' expedition of lSll!t-l!»(t(i. in charge of Dr. Alexander Agassiz, col- 

 lected 16 specimens which I am referring to /'. resptto-sa. The localities whence 

 they were obtained are as follows: Niau Island, Paumotu grouj), 4 specimens; 

 Fakarava Island. Paumotu group, 10 specimens; Makemo Island (reef in lagoon), 

 Paumotu group, 1 specimen; INIotee I'ta reef, Papeeti Harbor, Tahiti. 1 specimen. 

 In form these specimens show a range in variation somewhat similar to those from 

 the Hawaiian Islands. The terminal branchlets of the former, however, are in no 

 instance .so slender as those of the slenderest branches from the latter locality. 

 The South Pacific specimens are small, roilnded clumps, W'ith moderately stout 

 branches, rounded on the ends, or assume the growth form of the variety here called 

 sfylopJiordid'S. The calicular characters of the South Pacific specimens are decidedly 

 more constant than those of the Hawaiian specimens, the septa and columella are 

 uniformly obsolete or very rudimentary. The calices on the sides of the branches 

 and near the base are smaller and rather distant, similar in type to those of var. 

 I((ysanens!t<. A most careful comparison of the specimens from the two regions 

 failed to reveal anj- characters by which they could be separated, the South Pacific 

 specimens falling within the range of variation of those from the Hawaiian Islands, 

 but the former, judging from the material studied, are less variable. 



2. POCILLOPORA MOLOKENSIS, new species. 

 Plate XV: Plate XVI, tigs. 2, i<i. 



Corallum bush}-, of moderate size; a broken specimen has a greater diameter of 

 20 cm.; lesser, ItJ cm.; height, 12.5 cm. The branches are crooked and irregular in 

 shajie, ])end outward, and ultimately come to lie almost in a horizontal ))lane. They 

 look as if they had been pushed down from above, and therefore have an upper and 

 an under side. Their cross section is in .some instances subcircular, but usually it 

 is elliptical. They are larger at the base, the lesser diameter as much as 18 mm., or 

 even more, l)ecoming smaller distally. The tips may or may not be compres.sed. 



"Reef Corals, Chall. Kept., p. 66. 

 ftZool. .lalirb., Syst., IV, 1889, p. .533. 

 cProc. Zool. Soc. London, 1897, p. 943. 



