NarkativI': of Bahama Expedition. 215 



Among the cxrlenterales a great c^uantity of gorgonians 

 were secured, most of which have not yet been identitied. 

 Among them were Briarcuni ashestiiniui Pall., a heavy, fleshy 

 species of a pink or purplish color, and without a horn}- axis 

 cylinder. This is a good form to study, as the polyps are 

 large and will expand freely in aquaria. PlexaureUa diclioioma 

 is very common, with thick, fleshy branches covered with slit- 

 like apertures, and having the calicles included, and a well 

 marked axis cylinder. Eiiiiicca iouriicforti M. Edvv. has thick 

 branches and exserted calicles. The spicules of this gorgonian 

 are among the most beautiful of objects under the microscope, 

 being unusualh' large and brilliantly colored with pink and 

 red and purple. Eiiiiicca toiirucforti M. Edvv. is flabellate in 

 form, ver}' dark in color, and has non-retractile polyps. The 

 spicules are very large and massive, without coloration. Tiie 

 most beautiful of the gorgonians is Rliipidigorgici fiabcl/iiiii 

 Linn., the familiar •• sea-fan." The red variety sometimes 

 grows to a height of four feet, while the yellow specimens are 

 usually much smaller, seldom, if ever, attaining a height of 

 eighteen inches. .Yip/i/ovi-g-fa aiircps M. E. is also common, 

 with long branches resembling grass-like leaves of purple and 

 yellow. The polyps are arranged in linear series. 



The reef 'corals at Spanish Wells w^ere practically the same 

 as those found at the Tortugas, but several species were 

 more abund:int, notably Madrepora frolifcra Lam., of which 

 we secured a splendid series; Alyccdinm fragile Dana was 

 found here and not at the Tortugas. hophyJIia dipsarea x^g. 

 is interesting from the fact that it has enormous nematocysts 

 and affords, when alive, an excellent opportunity to study these 

 remarkable organs. The nettling cells are found in the ten- 

 tacles which surround the mouth of the polyp. It is hard to 

 determine just what kind of stimulus will cause the threads to 

 be projected. The writer has found that the tentacles may 

 be touched with a needle or buffeted by the squirmings of a 

 small worm without effect. On the other hand, he has seen 

 scores of them set off without any known cause. xA careful 

 study makes it evident that the threads are thrown out by 



