148 Natural History Bulletin. 



even extend into the tentacular papillee where they become 

 extremely mmute and lose their tubercles, appearing as simple 

 irregular rod-like bodies. All the spicules in the tentacles 

 occupy a definite portion of the mesoderm so that in a cross 

 section of a tentacle they are seen to occupy a zone immedi- 

 ately inside of the ectoderm. (See PI. VII, fig. 6, 1.) 



In the center of each of the small tentacular spicules a 

 well defined dot may be seen, and these dots appear to be pre- 

 cisely like the nuclei of the stellate mesodermal cells soon to 

 be described. 



3d. A cortical layer of small irregular spicules found im- 

 mediately under the ectodermal investment of the zoantho- 

 deme and tentacles. Many of these spicules look like grains 

 of sand under the microscope. They are calcareous, how- 

 ever, and not siliceous, and so are true spicules although they 

 have no regularity of form whatever. They are usually 

 about as long as broad and may have several rounded protu- 

 berances projecting from the main body. They form a com- 

 pact mass embedded in the mesoderm immediately below the 

 ectoderm of the entire zoanthodeme including the polyps. 

 They become smaller toward the tips of the tentacles where 

 they are indistinguishable from spicules of the second type. 



Taken as a whole, the spicules of this species offer a greater 

 diversity of size and form than those of any other species of 

 GoRGONiD^ discussed in this paper. They present the largest 

 and most densely tuberculate, as well as the smallest and 

 simplest types. Moreover, this is the only species in which 

 I have found three perfectly distinct types of spicules occupy- 

 ing equally well defined positions in the zoanthodeme. 



Basal substance is proportionately limited in quantity owing 

 to the great number of large spicules. In it are seen some- 

 what sparsely distributed stellate mesodermal cells. These are 

 more clearl}^ recognizable than in any other species studied 

 except Briareu'>n ashestiniim. Upon a cursory examination 

 under the microscope, nothing but the scattered, sharply de- 

 fined nuclei are seen. Upon closer inspection with a favorable 



