A. E. Verrill — Bermudian and West Indian Reef Corals. 137 



vexly rounded externally, where they pass into thick, stout costae, 

 bearing several conical, rough, often hollow spines. 



The summit is roughly serrate or spinulose ; the inner edge and 

 sides sharply and roughly granulated. The septo-costre are often 

 long, becoming thinner between the corallites than on their walls, 

 and alternately thicker and thinner ; they bear rather fine, strong, 

 suberect, acute or lacerate spines. Toward the margin of the coral 

 the corallites are smaller, more appressed, but circular, and have 6 to 

 12 larger, thick, prominent, exsert, acute, lacerate or spinose septa. 

 The septo-costse here become thinner and higher, with erect, rough 

 or lacerate, rather distant spines. The columella is generally pretty 

 well developed and roughly trabecular. 



In sections (fig. le) the exotheca is pretty compact, with numerous 

 rather small dissepiments, much smaller than in the next species. 



Tahiti; Mus. Comp. Zool.; Yale Mus.; Field Columb. Mus. 



For the older, thick form, with stout, swollen or rounded corallites, 

 I have used the variety name, turgida. It often looks like a dis- 

 tinct species, but it grades into the thinner form. The differences 

 are probably due to age. 



Mycedium tenuicostatum Ver., sp. nov. 



Plate XXIX. Figures 2, 2a, 2b, 2c. 



Coral forms a large foliaceous frond, more or less bent and irregu- 

 lar, considerably thickened and cellular in the older parts, but thin 

 at the margin. 



Exterior dichotomously costate ; the costae are unequal, 1 to 3 or 

 5 smaller ones between the larger ; all are broadly rounded, more 

 than twice as wide as the narrow intervening grooves ; their surfaces 

 are slightly rough with minute granules. 



Corallites, toward the center of the upper side, are large and much 

 crowded, expanded, prominent, often erect ; the larger ones are 15 to 

 18 mm across, with very exsert, excurved, very roughly lacerate and 

 spinose septa, which are thick and broad at the summit, with the 

 inner edge flaring and roughly dentate and the outer or costal por- 

 tion lacerately dentate. There are often 24 septa, in three cycles, 

 but frequently only 12 to 18 are present ; those of the third cycle 

 are thin and narrow ; sometimes smaller septa of the fourth eycle 

 appear. Many corallites are but little prominent, with the septa 

 thinner and not much exsert, angular at the summit, and roughly 



