MUSEUM OF COMPARATIVE ZOOLOGY. 53 



Halomitra tiara Agassiz, MS. 



Corallum solid, very convex above, much thinner than the preceding, 

 about half an inch thick. Septo-costal plates thin, short, strongly incise- 

 dentate, the teeth elongated, acute, granulated. Cells very distinct, irreg- 

 ularly scattered, but less remote than in the preceding, owing to the 

 much shorter plates, which are .3 of an inch long near the centre, and about 

 .6 near the margin. Lower surface very concave, with the costa; distinct to 

 the centre, close, slightly thickened, covered with nearly equal, sharp, conical 

 spines. — Kingsmills Islands ; A. Garret. 



Zoopilus echinatus Dana, Zoophytes, p. 319', pi. 21, fig. 6. 1846. 

 Feejee Islands ; J. D. Dana. 



This genus is perfectly well founded, being closely allied to Lithactinia ; 

 not, as Milne-Edwards has supposed, a Fungia. 



Trachypora Verrill. 



Corallum explanate, thin ; below echinate and coarsely costate ; above 

 with scattered polyp centres destitute of walls, with one or two cycles of 

 septa, radiating at the centres, but becoming subparallel between them, as 

 in Halomitra, strongly dentate or lacerately lobed, the strongest lobes sur- 

 rounding the polyp centres; columella loose, trabicular. 



This genus is in several respects intermediate between Halomitra and 

 Eclrinopora ; in its mode of growth it resembles the latter, but not in its 

 cells. It appears to include, besides the following, Eclrinopora aspera Dana 

 (Madrepora aspera Ellis and Sol.). 



Trachypora lacera Verrill. 



Broadly explanate and gibbous, thin, with many irregular openings near 

 the margin. Below coarsely and irregularly ribbed or costate, the principal 

 costa? very thick, prominent, strongly echinate, the spines irregular, lacer- 

 ately lobed, smaller intermediate costae scarcely spinose. Upper surface 

 covered by rather loose, very unequal septo-costal plates, which are deeply 

 and irregularly divided into strong lacerate spines; the plates are nearly 

 parallel, except close to the polyp centres, where they bend abruptly and 

 unite with the columella. The spines around the centres are large and 

 stout, often broad at the ends ; centres irregularly scattered, from half an 

 inch to an inch distant. — Singapore ; J. M. Barnard. 



Phyllastrea tubifex Dana. 1846. 



Syx. Mi/cedium tubifex M. Edw. and IIaime, 1851. — Feejee Islands; 

 J. D. Dana. 



This genus is quite distinct from Mycedium in its coarse, spinose septa, 

 and strong costa? beneath. 



Phyllastrea explanata Agassiz. MS. 



Differs from the preceding in its broadly explanate, thin, semicircular or 



