10G ACTINIANS FROM THE BAHAMA ISLANDS 



face without any apparent regularity, though more abundant upon the 

 oral than on the aboral surfaces. In section (pi., fig. i) these are seen 

 to be hollow outpushings of the wall of the tentacles. The wall of the 

 tentacle proper has a moderately thick mcsoglcea, the ectodermal and 

 endodermal muscle processes being rather low, the ectoderm possess- 

 ing but few nematocysts, -and the cndodcrm being thin with only a few 

 Zooxanthelke. The wall of the protrusion differs not a little from this; 

 thus the mesoglcea is much thinner, the muscle processes are aborted, 

 the ectoderm is richly provided with nematocysts, so that the protru- 

 sions might be termed batteries of nematocysts, and the endoderm is 

 thick and abundantly packed with Zooxanthellae. 



The tentacles leave exposed a considerable portion of the disk, 

 perhaps about half its breadth, and this portion is smooth and slightly 

 concave. Its mesoglcea is rather thin, and the muscle processes are but 

 moderate in length. No muscle cells are inclosed within the mesoglcea. 

 The mouth is not elevated above the disk, and is almost circular in the 

 preserved specimens, the gonidial angles being but slightly marked. 



In the single specimen in which I counted the mesenteries there were 

 forty-eight pairs, a number which agrees with that found by Dr. 

 Northrop in another specimen. Of these forty-eight pairs but six 

 are perfect, forming the first cycle; the six pairs of the second cycle 

 nearly equal the first cycle in size, but are imperfect ; the twelve of the 

 third cycle are considerably smaller, though still quite muscular; while 

 the twenty-four pairs of the fourth cycle, though extending some dis- 

 tance in from the body wall, yet have their musculature but feebly 

 developed. Two pairs of directives are present and are attached to a 

 greater extent of the stomatodaeum than are the other mesenteries of 

 the first cycle. The longitudinal muscles are well developed and have 

 in section the form represented in fig. 2. The parieto-basilar muscles 

 are but feebly represented and do not require special description. 

 Numerous acontia occur, a fact that was discovered by Dr. Northrop. 

 None of the specimens examined possessed reproductive organs, so 

 that nothing can be said regarding the distribution of these organs. 



There seems to be no room for doubt but that this form is identical 

 with that described by Duchassaing and Michelotti in their first paper 

 ('60) as Capnea lucida though later ('66) assigned to the genus Heter- 

 actis, a genus established by Milne-Edwards for the reception of the 

 Actinia aurora of Quoy and Gaimard. Andres ('83) has referred it to 



