114 THE BERMUDA ISLANDS. 



gonidial grooves are deep, and are prolonged some distance 

 below the rest of the stomatoda3um. Its mesogloea is much 

 thickened, and is devoid of processes upon its ectodermal sur- 

 face, being thus strongly contrasted with that of the stomato- 

 dseum. In its histology the ectoderm of the groove also differs 

 from that of the general stomatoda3um, the glandular cells 

 being evidently fewer in number, but the preservation of the 

 specimens was not sufficiently perfect to permit the details to 

 be made out. 



There are altogether twenty-four pairs of mesenteries, twelve 

 of which are perfect. The six primary pairs are united with 

 the stomatodseum to a greater extent than are the six secon- 

 daries, and the two pairs of directives have a much more ex- 

 tensive union than any of the other primary mesenteries, 

 owing to the great prolongation of the gonidial grooves. The 

 longitudinal muscle processes form a strongly projecting 

 though rather narrow band, the edges of which are sharply 

 defined, the processes being of equal length throughout the 

 muscular area, and diminishing abruptly towards the sides. 

 The mesoglcea of the portion of the mesenteries external to 

 the muscle bands is rather thick, and there is a strong parieto- 

 basilar muscle. Apparently only the mesenteries of the third 

 cycle, i.e. the imperfect mesenteries, are gonophoric, but my 

 preparations do not allow of certainty on this point. 



A few remarks are called for concerning the relationship of 

 this species. I was at first tempted to identify it with 0. 

 /ormosa,* but further consideration led me to separate it as a new 

 species. The fronds differ markedly from those of other 

 species of Oulactis. In these they have been described as 

 being " ddcoraces" a term which cannot be applied to the 

 fronds of 0. fasciculata. In it they consist of bunches of finger 

 or club-shaped hollow processes, the various processes of each 

 bunch being united by their base but distinct above. This 

 arrangement suggested the specific term which I have em- 



*Duchassaing and Micheloiti Mem. Keale Accademia di Torino. 2nd Ser. 

 xix, 1860, and xxiii, 1806. 



