16G AC'l'INI.K or Al,HA'rR(~>SS ]:X1'L()RAT10N8 MCMURRICH. 



16. Actineiniis plebeiirs, sp. nov. 

 Plat»^ x\i\ , Fius. 12-45. 



No. 711. Station L'Titl. T.at. oS' OS' S. ; loiifv. TjV 53' W. D.'ptli, G77 lathonis. 

 One .speiMUK'n. 



The b()<ly is calycilbiiii jiiul inrasiiros nbont 5'"" in lieiiiiht, with ii (li- 

 aiiietor of iibout 7"" at tlio disc. The base on the other hand measures 

 only -J.r)"" in di;nneter. It was jtrobably adherent, though from its 

 great distortion in the singlr spcrinien it is diHi<'vdt to l)e certain what 

 its charactei' may lia\e been. 



The column wall is rather soft in consistency, thongh relatively thick, 

 and its surface bcinj*- somewhat torn into threat' 'las a rather ragged 

 api)earance. The ectoderm is almost entirely macerated away, but the 

 few fragments that renniin show that it was of a chocolate brown color. 

 The sphincter is embedded in the mesoghea, not far from its endodermal 

 snrface. It exten<ls some distanct^ <h>wn tiie column wall, but is very 

 narrow. In sections ( IM. wiv, Kig. 4;>) it is seen to consist of a series of 

 cavities placed om^ above the othei', for the most ]>art in a single row, 

 each cavity being separated from its neighbor by a, distinct partition 

 of mesoghea. Each cavity is occupied by a mesoghral network of 

 line fibre, in the circular or oval interstices of which the muscle cells are 

 arranged. 



The margin is tentaculate and wavy or lobed in outline. The tenta- 

 cles are about ninety-six in number and are arranged in two or three 

 cycles at the nuirgin. They are of a ]>nrj>lish brown color and are 

 short and slender, each being provided at the outer surface of its 

 basewith a marked mesogheal thickening (PI. xxiv, Fig. 42), which ex- 

 tends a short distance npwards towards the tip npon the outer surface 

 of the tentacle. The longitudinal muscles are weak and are not em 

 bedded in the mesoghea. 



The disc is concave and of a wint'-puri>le cohw and is marke<l with 

 radiating ridges, due to the roofs of the inter- and intra-mesenterial 

 spaces being pouched out. The radiating muscles are ectodermal and 

 not at all embedded in the mesoghea. 



The mouth forms an elevation at the center of the disc. It is ]novided 

 with two well-marked siphonoglyplu'S. The stomatodanim is longitud- 

 inally ridged, the >valls of the deep siphon oglyphes being on the other 

 hand smooth. Tlie ecto(h'rm of the stomatodieum is of a deep wine- 

 purple color. 



The mesenteries are arranged in lour cycles, thongh indications of a 

 fifth and sixth cycle were present, neithci- of them being, however, per. 

 feet. In a sextant (»f the wall examiiu'd only one i»air of mesenteries of 

 the sixth cycle was ])resenl. and li\e pairs, instead of eight, of the tilth 

 cycle. Only the six i)airs of mesenteiics of the lirst cycle are perfect, 

 and only the mesenteries of the third and fourth cy<'les are gonophoric. 

 The mnscnlatur(>, both longitudinal and ]>arieto Itasilar, is very weak. 

 What <'orresiM)nds to tlie muscle ix'iinoii is very low, the mesoghea being 

 raised into short, blunt ]»rocesses which carry the muscle cells and give 



