HYDROZOA, SCYPHOZOA, ACTINOZOA, VERME8 WHITBLEGGB. 375 



thick at their origin and 2 cm. at their apex, their outer lateral 

 margins are thick, their inner ones thin and acute. The rest of the 

 upper margin consists of one broad lobe with three shallow in- 

 dentations. The general surface is uneven, having a few low 

 round or ridge-like elevations, and numerous shallow depressions 

 in which the very regular cyclosystems are situated. 



The gastropores are absent from the thick apical ridge, else- 

 where they are very evenly distributed ; they are on an average 

 about 2 mm. apart and 0-25 in diameter. The dactylopores are 

 generally confined to a limited area around the gastropores ; they 

 vary in number from four to six, their diameter is about (H2 mm. 

 and their distance from the central pore between 0'2 and 0'4 mm. 



The surface is minutely porous and reticulately ridged ; the ridges 

 are pretty regular, about 0'05 mm. apart. 



MILLEPORA PLATYPHYLLA, Ehrenberg. 



Millepora platyphylla, (Ehrenberg) Dana, U.S. Explor. Exped., 

 Zoophytes, p. 548, pi. Hi., fig. 5. 



A small fragment from the upper portion of a colony is in the 

 collection. 



The piece consists of three or four flat lamellae, two of which 

 have grown out vertically and at right angles to the main frond. 

 The lamellae are from 1 to 2 cm. in thickness, the apical margin 

 is somewhat thin and rounded, the lateral margins are acute. 



The surface is slightly tuberculous; the tubercles are low, rounded 

 and longitudinally arranged. 



Pores very unequally distributed, not distinctly arranged in 

 systems. Gastropores irregularly scattered, 0-2 mm. in diameter. 

 Dactylopores usually about O'l mm. in diameter, unevenly dis- 

 tributed over the whole colony. Surface reticulation with very 

 minute ridges, usually under O05 mm. apart. 



MILLEPORA NODOSA, Esper. 



Millepora nodosa, Esper, Die Pflanzenthiere, pi. ix. ; Moseley, 

 Chall. Rep. Zool., ii., p. 18, pi. xiii., tig. 3. 



There are several fine examples referable to this species ; of 

 these three are well marked forms differing considerably in habit, 

 but very similar in the cyclosystems and in the minute struc- 

 ture of the surface. 



Form A. The finest example possesses a large incrusting base 

 inclosing a mass of dead material of the same species. From the 

 upper surface there arises a series of irregular flattened lobes and 



