TRIBE I. ASTR^EACEA. 179 



and more coarsely toothed, and the exterior less regularly lamello- 

 striate. The branches are more crowded, the calicles having intervals 

 of about one-third of an inch between them. The larger lamellae pro- 

 ject about one-third of an inch above the margin of the cell. It 

 appears to be near the corymbosa, but differs in its polyps. 



6. MUSSA COSTATA. (Dana.) 



M. hemispherica, discis scepius suborHculatis. Corallum ramis crebris 

 caliculis -14" latis, vix turbinatis, elongatis ; extus, costato-angulatis, 

 raro dentatis ; lamellis valde incequalibus, dentatis, majoribus apice 

 late truncatis et scepe ^3-inciso-dentatis. 



Hemispherical; disks usually suborbiculate. Corallum having the 

 branches crowded ; calicles to 1 \ inches broad, scarcely turbinate, 

 elongate, exterior ribbed angular, with rarely a tooth ; lamellae very 

 unequal, dentate, the larger broad, truncate at apex, and often 

 2-3-gash-toothed. 



Plate 7, fig. 2, a calicle natural size ; 2 a, 2 b, lamellae. 



Tahiti, Society Islands. Exp. Exp. 



This species differs from the preceding in its truncate lamellae and 

 ribbed calicles, rarely dentate on the exterior. The calicles are usually 

 simple, and nearly straight, but sometimes one to three lobed, and are 

 from two to three inches long, with intervals between of one-eighth to 

 one-quarter of an inch. The larger lamellae are exsert about one-third 

 of an inch. 



II. Caliculato-ramosse ; cellis sscpe elongatis et sinuosis. 



7. MUSSA SINUOSA. (Lamarck.) 



M. hemispherica, discis elongatis meandrinis. Corallum ramis f-lj" 

 crassis, scepius valde compressis, extus striatis et longe serrato-dentatis ; 

 cellis interdum simplicibus, scepe sinuosis et 2-5" elongatis, lamellis 

 crassis, late dentatis et inciso-dentatis, J J" exsertis ; caliculis " se- 

 junctis. 



