70 bulletin: museum of comparative zoology. 



tubular, with complete inner walls. The length varies up to 5 mm., aperture above 

 the surface up to 2.5 mm. ; calicular diameter of the corallites about 1 mm., basal 

 1.5 mm. Walls perforate, sharply costate. The calices of the upper surface repre- 

 sent several types: (a) those between the bases of the branches are immersed; 

 (b) on the branches; apical corallites tubular, 1.5 mm. in diameter, projecting as 

 much ; calicular aperture .75 mm., walls sharply costate and perforate ; the lateral 

 calices are of at least three kinds, elongated, proliferous calices that may develop 

 branchlets ; ascending calices with very oblique apertures, height may be as much 

 as i mm., diameter about 1 mm. The inner wall is rarely or never so well devel- 

 oped as the outer, but it is rarely absent ; the outer lips of the calices are some- 

 times curved inward. In addition to the proliferous and simple ascending lateral 

 calices, there are immersed or subimmersed calices, which become more numerous 

 towards the base of the branch. 



Septa in the apical corallites, six ; in the lateral corallites of the branches the 

 directives are distinct, the others are usually rudimentary. The septa of the under 

 surface are very variable in development. There may be from less than six to two 

 complete cycles. 



Coenenchyma porous and echinulate. 



Locality : — Manga Reva. 



Remark : — This is the only vasiform Acropora whose calices have only six 

 septa known to me. 



Acropora aff. canaliculata (Klunzinger). 



Plate 5, Figs. 1-lb. 



1879. Madrepora canaliculata Klunzinger, Korallenth. Roth. Meer. 2, p. 12, 

 Plate 7, Fig. 3, Plate 4, Fig. 10, Plate 9, Fig. 8. 



I have been unable to decide positively to what species a piece of 

 a corallum from Manga Eeva should be referred. It belongs to Brook's 

 subgenus Tylopora, to Section C of that subgenus, and to subdivision h 

 of Section C. It groups with A. seriata, A. pyramidalis, and A. canali- 

 culata. I have considered it nearer to A. canaliculata because of prac- 

 tically complete agreement with Klunzinger's figures of the general 

 habit of the corallum, and the detail of a single branch, Plate 7, Fig. 3, 

 Plate 4, Fig. 10. As three figures are given of the Manga Reva speci- 

 men, a detailed description is not necessary. The branchlets are rather 

 thicker than Klunzinger's figures indicate, and the apical corallite is 

 4 mm. in maximum diameter. The radial calices are of three kinds ; 

 some are sunken, others in which the upper wall is wanting, and still 

 others with a developed upper wall, among the last are occasionally 

 some that are subtubular. The tubular calices are slightly dilated at 

 the mouth. No calices with a longitudinal slit in the upper wall, 

 such as is represented in Klunzinger's Plate 9, fig. 8 c-d, were seen ; 



